Alternative titles; symbols
HGNC Approved Gene Symbol: NKX2-5
SNOMEDCT: 218728005, 58140002, 7484005, 86299006; ICD10CM: Q20.1, Q21.3, Q25.21; ICD9CM: 745.11, 745.2, 747.11;
Cytogenetic location: 5q35.1 Genomic coordinates (GRCh38): 5:173,232,109-173,235,206 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 5q35.1 | Atrial septal defect 7, with or without AV conduction defects | 108900 | Autosomal dominant | 3 |
| Conotruncal heart malformations, variable | 217095 | 3 | ||
| Hypoplastic left heart syndrome 2 | 614435 | Autosomal dominant | 3 | |
| Hypothyroidism, congenital nongoitrous, 5 | 225250 | Autosomal dominant | 3 | |
| Tetralogy of Fallot | 187500 | Autosomal dominant | 3 | |
| Ventricular septal defect 3 | 614432 | Autosomal dominant | 3 |
Homeobox-containing genes play critical roles in regulating tissue-specific gene expression essential for tissue differentiation, as well as determining the temporal and spatial patterns of development. It has been demonstrated that a Drosophila homeobox-containing gene called 'tinman' is expressed in the developing dorsal vessel and in the equivalent of the vertebrate heart. Mutations in tinman result in loss of heart formation in the embryo, suggesting that tinman is essential for Drosophila heart formation. Furthermore, abundant expression of Csx, the presumptive mouse homolog of tinman, is observed only in the heart from the time of cardiac differentiation. CSX, the human homolog of murine Csx, has a homeodomain sequence identical to that of Csx and is expressed only in the heart, again suggesting that CSX plays an important role in human heart formation (summary by Shiojima et al., 1995).
Turbay et al. (1996) isolated the human CSX gene, which encodes a 324-amino acid protein.
Turbay et al. (1996) determined that the human CSX gene contains 2 exons.
Shiojima et al. (1995) mapped CSX to 5q34 near the boundary with 5q35, by fluorescence in situ hybridization and by a systematic screening of a YAC library using PCR. In this region, another homeobox-containing gene, MSX2 (123101), which is expressed in various tissues including the conduction system of the developing heart, has been assigned. Shiojima et al. (1995) suggested that localization of CSX and MSX2 to the same region of the genome may indicate that they are coordinately regulated during human heart formation. Kostrzewa et al. (1996) localized the CSX gene in a YAC contig of 5q34-q35 along with MSX2, DRD1 (126449), and DUSP1 (600714).
Turbay et al. (1996) mapped the CSX gene to chromosome 5q35, close to the junction with band 5q34. In the mouse the gene is located on chromosome 17 in the region of the t-locus (Himmelbauer et al., 1994). By somatic cell hybrid PCR analysis and by FISH, Turbay et al. (1996) found no evidence of location of CSX on chromosome 6 in the human.
The cardiac homeobox protein Nkx2.5 is essential in cardiac development, and mutations in CSX (which encodes Nkx2.5) cause various congenital heart malformations. Using the yeast 2-hybrid system with Nkx2.5 as bait, Hiroi et al. (2001) isolated the T box-containing transcription factor Tbx5 (601620); mutations in TBX5 cause the heart and limb malformations of Holt-Oram syndrome (142900). Cotransfection of Nkx2.5 and Tbx5 into COS-7 cells showed that they also associate with each other in mammalian cells. Glutathionine S-transferase (GST) pull-down assays indicated that the N-terminal domain and N-terminal part of the T box of Tbx5 and the homeodomain of Nkx2.5 are necessary for their interaction. Tbx5 and Nkx2.5 directly bound to the promoter of the gene encoding cardiac-specific natriuretic peptide precursor type A (NPPA; 108780) in tandem, and both transcription factors showed synergistic activation. Deletion analysis showed that both the N-terminal domain and the T box of Tbx5 are important for this transactivation. A G80R mutation of TBX5 (601620.0004), which causes substantial cardiac defects with minor skeletal abnormalities in Holt-Oram syndrome, did not activate Nppa or show synergistic activation, whereas R237Q (601602.0003), which causes upper-limb malformations without cardiac abnormalities (Basson et al., 1999), activated the Nppa promoter to an extent similar to that of wildtype Tbx5.
Habets et al. (2002) found that mouse Tbx2 (600747) and Nkx2.5 formed a complex on the Anf promoter and repressed Anf activity.
By microdissection of the mouse ventricular conduction system, followed by serial analysis of gene expression (SAGE) of the left bundle branch, Moskowitz et al. (2007) identified Id2 (600386) as a conduction system-specific transcript. Analysis of the Id2 promoter showed that conduction system-specific expression of Id2 was dependent on Nkx2.5 and Tbx5. Moskowitz et al. (2007) concluded that a molecular pathway including Id2, Nkx2.5, and Tbx5 coordinates specification of ventricular myocytes into the ventricular conduction system lineage.
Myotonic muscular dystrophy (DM1; 160900) is caused by an expansion of a (CTG)n repeat in the 3-prime UTR of the DMPK gene (605377). The mutation results in a toxic DMPK mRNA that is sequestered in the nucleus and alters the function of RNA splicing factors, causing aberrant splicing of target mRNAs. Individuals with DM1 have a proclivity for cardiac conduction abnormalities. Using a reversible transgenic mouse model of RNA toxicity in DM1, Yadava et al. (2008) showed that overexpression of a normal human DMPK 3-prime UTR with only (CUG)5 resulted in cardiac conduction defects, increased expression of Nkx2.5, and profound disturbances in connexin-40 (GJA5; 121013) and connexin-43 (GJA1; 121014). Overexpression of the DMPK 3-prime UTR in mouse skeletal muscle also induced transcriptional activation of Nkx2.5 and its targets. Human DM1 muscle, but not normal human muscle, showed similar aberrant expression of NKX2.5 and its targets. In mice, the effects on Nkx2.5 and its targets were reversed by silencing toxic RNA expression. Furthermore, haploinsufficiency of Nkx2.5 in Nkx2.5 +/- mice had a cardioprotective effect against defects induced by DMPK 3-prime UTR. Yadava et al. (2008) concluded that NKX2.5 is a modifier of DM1-associated RNA toxicity in heart.
By in situ hybridization in mouse embryos, Dentice et al. (2006) detected expression of Nkx2.5 in the ventral region of the pharynx and in the thyroid bud on embryonic day (E) 8.5. Nkx2.5 was expressed in the thyroid primordium up to E11.5; thereafter, Nkx2.5 transcript was no longer detected in the thyroid bud, whereas it was present in the heart region.
Congenital Cardiac Defects
Analyses of the tinman gene in Drosophila indicated that it has an essential role for specification of heart muscle progenitors in nascent mesoderm (Bodmer, 1993). Lyons et al. (1995) found that targeted disruption of a murine homolog of tinman, Nkx2.5, causes early embryonic lethality, with cardiac development arrested at the linear heart tube stage, prior to looping. Cardiac expression of Nkx2.5 continues throughout development and into adult life (Komuro and Izumo, 1993). Identification of human mutations that cause congenital heart disease offers a complementary approach to gene ablation studies and particularly fosters definition of gene defects that perturb later stages of cardiac development, such as cardiac septation. Studies of Holt-Oram syndrome, which has atrial septal defect (ASD) as a feature, showed that TBX5 (601620), a T-box transcription factor that is defective in that disorder, plays a role in septation.
Schott et al. (1998) analyzed the CSX gene in 4 families segregating autosomal dominant atrial septal defect associated with atrioventricular conduction defects (ASD7; 108900) and identified 3 different heterozygous mutations in the 4 families (600584.0001-600584.0003, respectively). Of 33 affected individuals, 27 had ASD; and atrioventricular conduction defects were present in all for whom clinical data were available. Eight of the patients had other structural heart defects as well, including ventricular septal defect (see VSD3, 614432), tetralogy of Fallot (TOF; 187500), subvalvular aortic stenosis, left ventricular hypertrophy, pulmonary atresia, and redundant mitral valve leaflets with fenestrations. Two of the mutations were predicted to impair binding of NKX2.5 to target DNA, resulting in haploinsufficiency, and a third potentially augmented target-DNA binding. These data indicated that NKX2.5 is important for regulation of septation during cardiac morphogenesis and for maturation and maintenance of atrioventricular node function throughout life.
To characterize further the role of NKX2.5 in cardiac morphogenesis, Benson et al. (1999) sought additional mutations in groups of probands with cardiac anomalies and first-degree AV block, idiopathic AV block, or tetralogy of Fallot. They identified 7 novel mutations by sequence analysis of the NKX2.5 coding region in 26 individuals (see, e.g., 600584.0004 and 600584.0005). Associated phenotypes included AV block, which was the primary manifestation of cardiac disease in nearly one-quarter of affected individuals, as well as atrial septal defect and ventricular septal defect. Ventricular septal defect was associated with tetralogy of Fallot or double-outlet right ventricle in 3 individuals. Ebstein anomaly (see 224700) and other tricuspid valve abnormalities were also present. Mutations in NKX2.5 cause a variety of cardiac anomalies and may account for a clinically significant portion of tetralogy of Fallot and idiopathic AV block. The coinheritance of NKX2.5 mutations with various congenital heart defects suggests that this transcription factor contributes to diverse cardiac developmental pathways.
Goldmuntz et al. (2001) genotyped a group of 114 patients with tetralogy of Fallot without 22q11 microdeletion (188400) and identified 4 heterozygous mutations in the NKX2-5 gene (600584.0004; 600584.0006-600584.0008) in 6 patients, none of whom had evidence of cardiac conduction system disease. Only 1 individual had a family history of TOF; however, a number of asymptomatic mutation carriers were identified in other families, indicating reduced penetrance. Goldmuntz et al. (2001) estimated that NKX2-5 mutations are present in approximately 4% of patients with TOF.
McElhinney et al. (2003) reported results from analysis of the NKX2-5 gene in 474 patients with congenital cardiac anomalies, including 114 patients previously reported by Benson et al. (1999) and Goldmuntz et al. (2001). In all, 12 distinct mutations were identified in 18 (3%) of 608 patients, including 2 patients with ASD without cardiac conduction defects (600584.0018; 600584.0019) and patients with conotruncal anomalies (217095) (see, e.g., 600584.0020) and hypoplastic left heart syndrome (HLHS2; 614435) (see, e.g., 600584.0004).
Gutierrez-Roelens et al. (2006) screened the NKX2-5 gene in 4 sporadic patients and 3 index cases of families with ASD and/or conduction defects, and identified a nonsense mutation (600584.0014) in affected members of a 3-generation family.
Among 230 patients with tetralogy of Fallot, Rauch et al. (2010) found that 2 patients (0.9%) had a low-penetrance mutation in the NKX2-5 gene (R25C; 600584.0004). Two additional patients had missense variants in the NKX2-5 gene (C270Y and V315L, respectively) that were not detected in 280 controls, but in vitro functional expression studies suggested no change in transcriptional activity as a result of these variants.
Stallmeyer et al. (2010) screened the NKX2-5 gene in 121 children with a broad spectrum of congenital heart malformations and identified heterozygosity for the R25C mutation (600584.0004) in 1 of 9 patients with hypoplastic left heart syndrome. In addition, heterozygosity for a missense mutation and a frameshift mutation were identified, respectively, in 2 probands with familial ASD and AV conduction defects.
Peng et al. (2010) analyzed the NKX2-5 gene in 135 Chinese pediatric patients with nonfamilial congenital cardiac defects and identified a heterozygous missense mutation (P283Q; 600584.0021) in 1 of 82 patients with ventricular septal defect (VSD3; 614432).
Chen et al. (2010) analyzed the NKX2-5 gene in 30 patients with nonsyndromic congenital heart defects, including 10 with VSD, 10 with ASD, 8 with VSD combined with ASD, and 2 with atrioventricular septal defects (AVSD). They identified a missense NKX2-5 variant in 1 patient with VSD (600584.0023).
Wang et al. (2011) screened 136 Chinese probands with VSD for mutations in NKX2-5 and identified heterozygosity for a missense mutation (P59A; 600584.0022) in 1 (0.74%) of 136 probands. The proband's affected sister and father also carried the mutation, which was not found in 200 ethnically matched controls.
For a detailed discussion of a family with left ventricular noncompaction (LVNC) that segregated with mutations in the MYH7 (160760), MKL2 (609463), and NKX2-5 genes, see LVNC5 (613426).
Nongoitrous Congenital Hypothyroidism 5
Dentice et al. (2006) found that Nkx2.5-null mouse embryos exhibited thyroid bud hypoplasia, providing evidence that NKX2-5 plays a role in thyroid organogenesis and that NKX2-5 mutations contribute to thyroid dysgenesis (see 225250). NKX2-5 mutation screening in 241 patients with congenital nongoitrous hypothyroidism (see CHNG5, 225250) identified 3 heterozygous missense changes in 4 patients (see 600584.0004 and 600584.0015-600584.0016). Functional characterization of the 3 mutations demonstrated reduced DNA binding and/or transactivation properties, with a dominant-negative effect on wildtype NKX2E.
Systemic Lupus Erythematosus
For discussion of an association between variation in the NKX2-5 gene and systemic lupus erythematosus, see 152700.
Reclassified Variants
The IVS1+1G-T variant in the NKX2-5 gene (600584.0005) has been reclassified as a variant of unknown significance. Benson et al. (1999) had identified this variant in a patient with idiopathic second-degree atrioventricular block.
The E21Q variant in the NKX2-5 gene (600584.0006) has been reclassified as a variant of unknown significance. Goldmuntz et al. (2001) had identified this variant in a patient with tetralogy of Fallot (187500).
The P236H variant in the NKX2-5 gene (600584.0024) has been reclassified as a variant of unknown significance. Koss et al. (2012) had identified this variant in a family segregating isolated congenital asplenia (ICAS; 271400).
Somatic Mutations
By direct sequencing, Reamon-Buettner and Borlak (2004) analyzed the NKX2-5 gene in the diseased heart tissues of 68 patients with complex congenital heart disease, focusing particularly on atrial, ventricular, and atrioventricular septal defects. They identified 35 nonsynonymous NKX2-5 mutations (see, e.g., 600584.0011) in the diseased heart tissues of patients. These mutations were mainly absent in normal (i.e., unaffected) heart tissue of the same patient, indicating the somatic nature and mosaicism of the mutations. The authors also observed multiple mutations and multiple haplotypes, as well as mutations in Down syndrome (190685) patients with cardiac malformations. They concluded that somatic mutations in transcription factor genes of cardiac progenitor cells provide a novel mechanism of disease. Youssoufian and Pyeritz (2002) and Erickson (2003) had commented on the significance of somatic mutations during early embryogenesis. Disease-associated or disease-causing somatic mutations are undetected by genetic analysis of lymphocytic or lymphocyte DNA alone, and mosaicism may reduce the likelihood of detection in the affected tissue.
Inga et al. (2005) developed a functional yeast assay capable of determining transactivation capacity and specificity of expressed NKX2-5 alleles towards targeted response element sequences. They found that mutations in the third helix of the homeodomain, which provides DNA binding specificity, are associated with either ventricular or atrioventricular septal defects. Individual mutants exhibited partial (600584.0008) to complete (600584.0001; 600584.0017) loss of function and differences in transactivation capacity between the various response elements. The mutants also exhibited gene dosage rather than dominant effects on transcription. Inga et al. (2005) concluded that somatic mutations in the binding domains of NKX2-5 are associated specifically with AVSD or VSD and result in loss of protein function.
In diseased cardiac tissues from 2 of 52 explanted hearts of unrelated patients with complex cardiac malformations, notably ventricular and atrioventricular septal defects, Reamon-Buettner and Borlak (2006) found 3 nonsynonymous mutations in the HEY2 gene (604674). Since the 2 AVSD patients carried also binding domain mutations in other cardiac-specific transcription factors, e.g., NKX2-5, TBX5, and GATA4 (600576), Reamon-Buettner and Borlak (2006) concluded that breakdown of combinatorial interactions of transcription factors may have contributed to the complexity of their cardiac malformations.
Pauli et al. (1999) described a distal 5q deletion, del(5)(q35.1q35.3), in a 7.5-year-old girl who, in addition to atrial septal defect and patent ductus arteriosus (see 607411), which were both repaired in infancy, had ventricular myocardial noncompaction (604169). FISH showed that this deletion included the locus for CSX. This led Pauli et al. (1999) to suggest that some instances of ventricular myocardial noncompaction may be caused by haploinsufficiency of CSX. They reviewed 4 other cases with deletions in the same region of 5q and pointed out that 2 of them had atrial septal defects and 1 had a cardiomyopathy.
Jay et al. (2004) found that the number of cells in the cardiac conduction system of Nkx2-5 knockout mice was directly related to gene dosage. Null mutant embryos appeared to lack the primordium of the AV node; in Nkx2-5 haploinsufficiency, the conduction system had half the normal number of cells. In addition, an entire population of connexin40-/connexin45+ (CX40; 121013/CX45) cells was missing in the AV node of Nkx2-5 heterozygous KO mice. Jay et al. (2004) stated that specific functional defects associated with Nkx2-5 loss of function could be attributed to hypoplastic development of the relevant structures in the conduction system. Surprisingly, the cellular expression of CX40, the major gap junction isoform of Purkinje fibers and a putative NKX2E target, was unaffected, consistent with normal conduction times through the His-Purkinje system measured in vivo. Jay et al. (2004) concluded that postnatal conduction defects in NKX2E mutation may result, at least in part, from a defect in the genetic program that governs the recruitment or retention of embryonic cardiac myocytes in the conduction system.
Pashmforoush et al. (2004) generated mice with a ventricular-restricted knockout of Nkx2.5. These mice displayed no structural defects, but had the progressive complete heart block and massive trabecular muscle overgrowth found in some patients with NKX2.5 mutations. At birth, mutant mice displayed a hypoplastic AV node and then developed selective dropout of these conduction cells. Transcriptional profiling uncovered aberrant expression of a unique panel of atrial and conduction system-restricted target genes, as well as ectopic high-level Bmp10 (608748) expression in the adult ventricular myocardium. Further, Bmp10 was shown to be necessary and sufficient for a major component of the ventricular muscle defects. The authors concluded that loss of ventricular muscle cell lineage specification into trabecular and conduction system myocytes is a novel mechanistic pathway for progressive cardiomyopathy and conduction defects in congenital heart disease.
Pulmonary venous vessels are sheathed by a myocardial cell layer called the pulmonary myocardium. Mommersteeg et al. (2007) found that Pitx2c (601542)-null mice failed to develop a pulmonary myocardial sleeve due to the absence of pulmonary myocardial cell precursors. Genetic labeling demonstrated that the pulmonary myocardium arose from Nkx2.5-expressing precursors, while the systemic venous return arose from Nkx2.5-negative precursors. In the pulmonary myocardium of mice hypomorphic for Nkx2.5, expression of Pitx2 was unaltered, but expression of the Nkx2.5 target Cx40 was downregulated, and expression of the systemic venous return pacemaker channel Hcn4 (605206) was upregulated, resulting in a phenotype that partly resembled that of the systemic venous return. Mommersteeg et al. (2007) concluded that NKX2.5 and PITX2C play critical roles in the formation and identity of the pulmonary myocardium.
Nimura et al. (2009) showed that the H3K36me3-specific histone methyltransferase Whsc1 (602952) functions in transcriptional regulation together with developmental transcription factors whose defects overlap with the human disease Wolf-Hirschhorn syndrome (WHS; 194190). Nimura et al. (2009) found that mouse Whsc1, 1 of 5 putative Set2 homologs, governed H3K36me3 along euchromatin by associating with the cell type-specific transcription factors Sall1 (602218), Sall4 (607343), and Nanog (607937) in embryonic stem cells, and Nkx2-5 in embryonic hearts, regulating the expression of their target genes. Whsc1-deficient mice showed growth retardation and various WHS-like midline defects, including congenital cardiovascular anomalies. The effects of Whsc1 haploinsufficiency were increased in Nkx2-5 heterozygous mutant hearts, indicating their functional link. Nimura et al. (2009) proposed that WHSC1 functions together with developmental transcription factors to prevent the inappropriate transcription that can lead to various pathophysiologies.
Koss et al. (2012) found expression of the Nkx2-5 gene in the visceral mesoderm of embryonic mice, where the spleen anlage arises. Mice with splenic mesenchymal-specific knockout of Pbx1 (176310) developed hyposplenia due to a defect in mesenchymal cell proliferation. Conditional knockout of Pbx1, which controls Nkx2-5 expression, resulted in decreased expression of Nkx2-5 and hyposplenia, indicating that Nkx2-5 is critical for splenic growth. Pbx1 was found to repress the cell cycle inhibitor CDKN2B (600431) in the spleen anlage; loss of Pbx1 in cultured spleen mesenchymal cells caused upregulation of Cdkn2b and reduced proliferation of these cells. Splenic expansion could be partially rescued by genetic ablation of Cdkn2b. Thus, repression of Cdkn2b by Pbx1 is required for proper organ morphogenesis and growth in vivo. Nkx2-5 was also shown to bind to and repress Cdkn2b. The findings delineated a regulatory module governing mammalian spleen organogenesis that involves Pbx1, Nkx2-5, and Cdkn2b.
Schulkey et al. (2015) found that the impact of maternal age on congenital heart disease can be modeled in mouse pups that harbor a mutation of the cardiac transcription factor gene Nkx2-5. Using reciprocal ovarian transplants between young and old mothers, Schulkey et al. (2015) established a maternal basis for the age-associated risk in mice. A high-fat diet did not accelerate the effect of maternal aging, so hyperglycemia and obesity do not simply explain the mechanism. The age-associated risk varied with the mother's strain background, making it a quantitative genetic trait. Most remarkably, voluntary exercise, whether begun by mothers at a young age or later in life, can mitigate the risk when they are older. Schulkey et al. (2015) concluded that even when the offspring carry a causal mutation, an intervention aimed at the mother can meaningfully reduce their risk of congenital heart disease.
In 2 large 5-generation families with congenital heart disease (predominantly atrial septal defect of the secundum type) and atrioventricular conduction abnormalities (ASD7; 108900), one of which (family MXP) was originally reported by Pease et al. (1976), Schott et al. (1998) found a C-to-T transition at CSX nucleotide 642, which was predicted to substitute a methionine codon (ATG) for the highly conserved threonine codon (ACG) at homeodomain position 41; the mutation was designated thr178 to met (T178M). In family MXP, 5 of 13 affected individuals had additional congenital heart defects, including ventricular septal defect in 2 patients, tetralogy of Fallot in 2 (associated with pulmonary atresia in 1), and subvalvular aortic stenosis with left ventricular hypertrophy in 1. The last mentioned patient underwent sudden death; 3 other affected individuals in this family had also died, 1 at 3 days of life, 1 postoperatively, and 1 of heart failure years after surgical correction of tetralogy of Fallot and pacemaker implantation. Two other affected individuals also had pacemakers implanted. In the second family, the 8 affected individuals did not manifest other cardiac defects; 7 had pacemakers implanted, and there were no sudden deaths.
In a male patient with ASD secundum and AV block that progressed to Wenckebach-type second-degree heart block (108900), Hirayama-Yamada et al. (2005) identified the T178M mutation. The patient's mother had the same mutation and ASD with atrial fibrillation; other members of the family had ASD and conduction defects as well, although his 2 sibs had only arrhythmias without cardiac malformations.
Inga et al. (2005) showed that the T178M mutation resulted in a loss-of-function for all response elements tested using a yeast-based functional assay.
In a 4-generation family with atrial septal defect secundum and atrioventricular conduction defects (ASD7; 108900), Schott et al. (1998) found a heterozygous sequence change in the CSX gene that encoded a truncated NKX2.5 protein. A C-to-T transition at nucleotide 618 was predicted to substitute a termination codon (TAG) for a glutamine (CAG) codon, which would stop translation prematurely at position 33 of the homeodomain. The mutation was designated gln170 to ter (Q170X). One of the 6 affected members of this family also had left ventricular hypertrophy; 2 affected individuals underwent sudden death.
In a 4-generation family with atrial septal defect secundum and atrioventricular conduction defects (ASD7; 108900), Schott et al. (1998) identified a C-to-T transition at nucleotide 701 of the NKX2-5 gene, which was predicted to create a termination signal immediately COOH-terminal to the homeodomain. The mutation was designated gln198 to ter (Q198X). Although 2 other NKX2-5 mutations (600584.0001, 600584.0002) were predicted to alter the affinity or sequence-specificity of target DNA binding, implying that NKX2.5 haploinsufficiency causes the syndrome, the Q198X mutation was predicted to increase transcription of reporter genes and therefore may function as an activating mutation that aberrantly augments transcription of downstream genes. Two of the 6 affected members of this family also had left ventricular hypertrophy, 1 with mitral valve fenestration as well; both underwent sudden death, as did a third affected individual. The 3 surviving affected members of the family all had pacemakers implanted.
Hosoda et al. (1999) found the same mutation in a 59-year-old Japanese man who likewise had familial atrial septal defect and atrioventricular conduction disturbance. At age 45, the patient suffered Adams-Stokes syncope due to atrial fibrillation with slow ventricular response and was found to have ASD. Thereafter he had simultaneous surgical ASD closure and permanent pacemaker implantation. One of his 2 sons also had ASD and he too had had surgical ASD closure and permanent pacemaker implantation, but died at the age of 18 from pneumonia.
Congenital Cardiac Defects
In a female patient with tetralogy of Fallot (TOF; 187500) who was negative for del(22q11), Benson et al. (1999) identified heterozygosity for a 182C-T transition in the 5-prime coding region of the NKX2-5 gene, resulting in an arg25-to-cys (R25C) substitution that changes a highly conserved amino acid from basic to neutral. The mutation was not found in 100 control chromosomes from a randomly selected population. The patient, who had undergone surgical repair of typical TOF and 2 small muscular ventricular septal defects at 1 year of age, did not have atrioventricular block or atrial septal defect.
Kasahara et al. (2000) demonstrated impaired DNA binding of the R25C variant CSX peptide to dimeric sites.
Goldmuntz et al. (2001) identified the R25C mutation in 3 unrelated probands with tetralogy of Fallot who were negative for del(22q11). None of the patients had atrioventricular conduction abnormalities. The father of 1 of the probands was also heterozygous for the R25C mutation and had a history of ventricular septal defect.
McElhinney et al. (2003) screened the NKX2-5 gene in 474 patients with congenital cardiac defects and identified heterozygosity for the R25C mutation in 1 (4%) of 23 patients with interrupted aortic arch (see 217095), 1 (4%) of 22 patients with truncus arteriosus (see 217095), and 1 (1%) of 80 patients with hypoplastic left heart syndrome (HLHS2; 614435).
In 2 (0.9%) of 230 patients with TOF, Rauch et al. (2010) identified heterozygosity for the R25C mutation.
In 1 of 9 patients with hypoplastic left heart syndrome, Stallmeyer et al. (2010) identified heterozygosity for the R25C mutation. The complete cardiac phenotype of the male infant included atresia of the aortic and mitral valves and a small VSD that required corrective surgery.
In 2 sporadic Italian patients with TOF associated with a left-sided arch, subaortic ventricular septal defect, and patent pulmonary valve, De Luca et al. (2011) identified the R25C mutation in the NKX2-5 gene. Parental DNA was unavailable for analysis; the mutation was not found in 500 population-matched controls.
Congenital Nongoitrous Hypothyroidism 5
In a 24-year-old woman with thyroid ectopy and a 15-year-old boy with athyreosis of the gland (see CHNG5, 225250), Dentice et al. (2006) identified a heterozygous 73C-T transition in the NKX2-5 gene, resulting in an R25C substitution. The mutation in each case was inherited from a parent. Neither patient had a history of cardiac disease; the boy showed bilateral cortex atrophy at birth and had attention deficit hyperactivity disorder. The mutation, which was identified in 1 of 561 control individuals, exhibited significant functional impairment, with reduction of transactivation properties and dominant-negative effect. In addition, the results indicated that although the R25C mutant normally also binds the DIO2 (601413) promoter, its activity on the DIO2, TG (188450), and TPO (606765) promoters is significantly impaired.
This variant, formerly titled ATRIOVENTRICULAR BLOCK, IDIOPATHIC SECOND-DEGREE, has been reclassified because its contribution to the phenotype has not been confirmed.
One of the groups of cardiac cases studied by Benson et al. (1999) in an evaluation of the role of CSX comprised 10 probands who had been treated with a pacemaker for idiopathic second- or third-degree AV block. None had a previous history of any other cardiac surgery or other evidence of heart disease. None of the mothers of the 10 probands had autoantibodies to SSA/Ro (109092) or SSB/La ribonucleoprotein (109090). However, a history of heart disease under the age of 40 years in at least 1 other family member was identified in 6 cases and included AV conduction disturbance, atrial fibrillation, or sudden death. Only 1 of the 10 probands was found to have a mutation in the CSX gene, a G-to-T transversion in the first position of the splice donor site of intron 1. No phenotypic feature of this individual distinguished him from others in the group. He presented at 12 years of age with a 1-year history of recurrent syncope. Advanced second-degree AV block was identified on ECG; no other cardiac abnormalities were noted. Pacemaker implantation was performed. Evaluation of his mother and 2 younger brothers was normal, and none carried the mutation. His father (not genotyped) had died suddenly, presumably because of arrhythmias, at 29 years of age. His heart weight was 300 g, and no major abnormalities were noted at autopsy.
This variant, formerly titled TETRALOGY OF FALLOT, has been reclassified because its contribution to the phenotype has not been confirmed.
Goldmuntz et al. (2001) reported a glu-to-gln substitution at the highly conserved codon 21 position (E21Q) of the CSX gene in an individual with tetralogy of Fallot (TOF; 187500) characterized by a right-sided aortic arch, mirror-image aortic arch branching, and a retroaortic innominate vein. This individual's mother and maternal grandmother were also found to carry this variant, but neither manifested congenital heart disease. The authors concluded that this mutation was likely to represent a pathologic sequence change with reduced penetrance.
Goldmuntz et al. (2001) reported an arg-to-cys substitution at the highly conserved codon 216 position (R216C) of the CSX gene in an individual with tetralogy of Fallot (TOF; 187500) and right-sided aortic arch. No data regarding other family members was presented.
Goldmuntz et al. (2001) reported an ala-to-val substitution at the highly conserved codon 219 position (A219V) of the CSX gene in an individual with tetralogy of Fallot (TOF; 187500) with pulmonary valve atresia without major aortopulmonary collateral arteries, right-sided aortic arch, and mirror-image aortic arch branching. The patient's mother was also found to carry this variant but was clinically normal. The authors concluded that this mutation was likely to represent a pathologic sequence change with reduced penetrance.
Inga et al. (2005) noted that the A219V mutation is located in the NK2-specific domain and showed that this mutation resulted in a mild reduction of function for all response elements tested using a yeast-based functional assay. They suggested that the germline A219V mutation is a risk factor that when combined with somatic NK2-5 mutations can increase the likelihood of congenital heart disease.
In 5 affected members of a family with atrial septal defect and atrioventricular conduction defects (ASD7; 108900), Watanabe et al. (2002) identified a 7-bp deletion in exon 1 of the NKX2-5 gene, 215delAGCTGGG, resulting in a frameshift and a truncated protein lacking a homeodomain. Surgical closure of the atrial septal defect had been performed in 4 of the genotype-positive members, in 3 of whom sinus venosus ASD had been identified. In addition, 1 of these 4 had a double orifice mitral valve and underwent mitral valve replacement at the time of ASD surgery. ECG evidence of AV block was confirmed in 4 patients; in 2 patients, this manifested as Mobitz type I second-degree block and was associated with atrial fibrillation. In 1 patient, atrial fibrillation was first noted 28 years after ASD surgery, and in another patient atrial fibrillation, first noted at age 46 years, was the sole manifestation of cardiac disease. Additionally, 1 member of the family heterozygous for the mutation was found to have polysplenia and a midline, symmetric liver by CT; malrotation was diagnosed by a barium x-ray study that showed the ascending colon and cecum were shifted to the midline and forward with the small intestine on the left.
In 4 affected members of a family with atrial septal defect and atrioventricular conduction defects (ASD7; 108900), Watanabe et al. (2002) identified a 2-bp deletion in exon 1 of the NKX2-5 gene, 223delCG, resulting in a frameshift with a premature stop codon. Surgical closure of a secundum ASD had been performed in 3 members of the family. All 3 had ECG evidence of first- or second-degree AV block. In 1 member of the family, first-degree AV block was the only manifestation of heart disease.
In the DNA of cardiac tissues from 36 of 68 patients with complex congenital heart disease, focusing particularly on atrial (108900), ventricular, and atrioventricular septal (606215) defects, Reamon-Buettner and Borlak (2004) identified a 1072A-G transition in exon 2 of the NKX2-5 gene, resulting in an asp299-to-gly (D299G) substitution. The mutation was identified in patients with or without Down syndrome (190685).
In affected sibs from a family with atrial septal defect and atrioventricular conduction defects (ASD7; 108900), Hirayama-Yamada et al. (2005) identified a 1-bp deletion (262delG) in exon 1 of the NKX2-5 gene, resulting in a frameshift and premature termination at codon ala88 predicted to truncate the protein without the homeodomain and C terminus.
In a female patient with a combination secundum- and cribriform-type atrial septal defect at age 7 who later developed atrioventricular conduction block (ASD7; 108900), Hirayama-Yamada et al. (2005) identified a 568C-T transition in exon 2 of the NKX2-5 gene, resulting in an arg190-to-cys (R190C) substitution.
In affected members of a 3-generation family with atrial septal defect and/or atrioventricular block (ASD7; 108900), Gutierrez-Roelens et al. (2006) identified a 768T-A transversion in the NKX2-5 gene, resulting in a tyr256-to-ter (Y256X) substitution. The conduction defect in affected members of this family always resided in the AV node; 3 patients also had atrial fibrillation, and 1 had unexplained ventricular tachycardia seen on Holter monitoring. The mutation was not found in 110 unrelated controls.
In a 13-year-old girl with an ectopic thyroid and severe hypothyroidism (CHNG5; 225250), who had no documented congenital heart defect, Dentice et al. (2006) identified a heterozygous 335G-T transversion in the NXK2E gene, resulting in an ala119-to-ser substitution a few residues upstream from the beginning of the homeodomain. The mutation was inherited from the mother, who exhibited autoimmune hypothyroidism and was on lifelong treatment with L-T4, and was not observed among 561 controls. The mutation exhibited a significant functional impairment, with reduction of transactivation properties and dominant-negative effect, which was associated with reduced DNA binding.
In a 6-year-old girl with thyroid ectopy and hypothyroidism (CHNG5; 225250), Dentice et al. (2006) identified a heterozygous 482G-C transversion in the NKX2-5 gene, resulting in an arg161-to-pro (R161P) substitution within the homeodomain. The patient exhibited patent foramen ovale at birth that resolved spontaneously and minor mitral valve insufficiency. She inherited the mutation from her father, who also had minor mitral valve insufficiency. The mutation exhibited a significant functional impairment, with reduction of transactivation properties and dominant-negative effect, which was associated with reduced DNA binding.
In 22 of 23 formalin-fixed heart samples from deceased patients with atrioventricular septal defects (606215), Inga et al. (2005) identified a lys183-to-glu (K183E) mutation in the homeodomain (HD) of the NKX2-5 gene. Yeast-based functional assay showed that K183E resulted in loss-of-function for all response elements tested. None of the samples from deceased patients with ventricular septal defects had the K183E mutation; however, 14 of 29 had at least 1 mutation in the third helix of the HD, leading to either inactivation or reduction of NKX2-5 transactivation.
In a patient with atrial septal defect without atrioventricular conduction defects (ASD7; 108900), McElhinney et al. (2003) identified heterozygosity for a 44A-T transversion in the NKX2-5 gene, resulting in a lys15-to-ile (K15I) substitution within the conserved TN domain. An unaffected parent was also heterozygous for the mutation, consistent with decreased penetrance, and the mutation was not found in 100 control chromosomes.
In a patient with atrial septal defect without atrioventricular conduction defects (ASD7; 108900), McElhinney et al. (2003) identified heterozygosity for a 380C-A transversion in the NKX2-5 gene, resulting in an ala127-to-glu (A127E) substitution located just 5-prime to the homeodomain. An unaffected parent was also heterozygous for the mutation, consistent with decreased penetrance, and the mutation was not found in 100 control chromosomes.
In a patient with double-outlet right ventricle (DORV; see 217095), McElhinney et al. (2003) identified heterozygosity for a 3-bp deletion (871delAAC), resulting in deletion of an asn residue at codon 291 (291delN) immediately 3-prime to the conserved carboxy-terminal NK2 domain.
In a Chinese pediatric patient with ventricular septal defect (VSD3; 614432), Peng et al. (2010) identified heterozygosity for an 848C-A transversion in exon 2 of the NKX2-5 gene, resulting in a pro283-to-gln (P283Q) substitution in the C-terminal region. The mutation was not found in 114 controls.
In a father, son, and daughter from a 3-generation Chinese family with ventricular septal defect (VSD3; 614432), Wang et al. (2011) identified heterozygosity for a 175C-G transition in the NKX2-5 gene, resulting in a pro59-to-ala (P59A) substitution at a highly conserved residue. The mutation was not found in unaffected family members or in 200 ethnically matched controls. Transfection studies in COS-7 cells with the P59A mutant demonstrated significantly reduced activation of a direct cardiac downstream target gene, ANP (NPPA; 108780), compared to wildtype NKX2-5.
In a patient with ventricular septal defect (VSD3; 614432), Chen et al. (2010) identified heterozygosity for a 998C-G transversion in the NKX2-5 gene, resulting in a pro257-to-ala (P257A) substitution. The mutation was not found in 100 controls.
This variant, formerly titled ASPLENIA, ISOLATED CONGENITAL (271400), has been reclassified based on the findings of Bolze et al. (2013).
In 3 members of a family of African descent with isolated congenital asplenia (ICAS; 271400), Koss et al. (2012) identified a heterozygous 707C-A transversion in exon 2 of the NKX2-5 gene, resulting in a pro236-to-his (P236H) substitution at a highly conserved residue immediately adjacent to a conserved tyrosine-rich domain. The family had been reported as family E by Mahlaoui et al. (2011). Western blot analysis showed that the mutant protein was produced and bound to DNA similar to wildtype. However, transfection of the mutation into HEK293 cells showed that the mutant construct had decreased transactivation activity compared to control, as measured by luciferase. Studies in mouse embryos and cellular studies of splenic mesenchymal cells demonstrated a pivotal role for the NKX2-5 gene in spleen development.
In a study of families with isolated congenital asplenia, Bolze et al. (2013) identified a heterozygous missense mutation in the RPSA gene (150370.0005) in affected members of this family. They identified heterozygous mutations in the RPSA gene in a total of 18 patients from 8 kindreds.
Basson, C. T., Huang, T., Lin, R. C., Bachinsky, D. R., Weremowicz, S., Vaglio, A., Bruzzone, R., Quadrelli, R., Lerone, M., Romeo, G., Silengo, M., Pereira, A., Krieger, J., Mesquita, S. F., Kamisago, M., Morton, C. C., Pierpont, M. E. M., Muller, C. W., Seidman, J. G., Seidman, C. E. Different TBX5 interactions in heart and limb defined by Holt-Oram syndrome mutations. Proc. Nat. Acad. Sci. 96: 2919-2924, 1999. [PubMed: 10077612] [Full Text: https://doi.org/10.1073/pnas.96.6.2919]
Benson, D. W., Silberbach, G. M., Kavanaugh-McHugh, A., Cottrill, C., Zhang, Y., Riggs, S., Smalls, O., Johnson, M. C., Watson, M. S., Seidman, J. G., Seidman, C. E., Plowden, J., Kugler, J. D. Mutations in the cardiac transcription factor NKX2.5 affect diverse cardiac developmental pathways. J. Clin. Invest. 104: 1567-1573, 1999. [PubMed: 10587520] [Full Text: https://doi.org/10.1172/JCI8154]
Bodmer, R. The gene tinman is required for specification of the heart and visceral muscles in Drosophila. Development 118: 719-729, 1993. [PubMed: 7915669] [Full Text: https://doi.org/10.1242/dev.118.3.719]
Bolze, A., Mahlaoui, N., Byun, M., Turner, B., Trede, N., Ellis, S. R., Abhyankar, A., Itan, Y., Patin, E., Brebner, S., Sackstein, P., Puel, A., and 20 others. Ribosomal protein SA haploinsufficiency in humans with isolated congenital asplenia. Science 340: 976-978, 2013. [PubMed: 23579497] [Full Text: https://doi.org/10.1126/science.1234864]
Chen, Y., Mao, J., Sun, Y., Zhang, Q., Cheng, H.-B., Yan, W.-H., Choy, K. W., Li, H. A novel mutation of GATA4 in a familial atrial septal defect. Clin. Chim. Acta 411: 1741-1745, 2010. [PubMed: 20659440] [Full Text: https://doi.org/10.1016/j.cca.2010.07.021]
De Luca, A., Sarkozy, A., Ferese, R., Consoli, F., Lepri, F., Dentici, M. L., Vergara, P., De Zorzi, A., Versacci, P., Digilio, M. C., Marino, B., Dallapiccola, B. New mutations in ZFPM2/FOG2 gene in tetralogy of Fallot and double outlet right ventricle. Clin. Genet. 80: 184-190, 2011. [PubMed: 20807224] [Full Text: https://doi.org/10.1111/j.1399-0004.2010.01523.x]
Dentice, M., Cordeddu, V., Rosica, A., Ferrara, A. M., Santarpia, L., Salvatore, D., Chiovato, L., Perri, A., Moschini, L., Fazzini, C., Olivieri, A., Costa, P., Stoppioni, V., Baserga, M., De Felice, M., Sorcini, M., Fenzi, G., Di Lauro, R., Tartaglia, M., Macchia, P. E. Missense mutation in the transcription factor NKX2-5: a novel molecular event in the pathogenesis of thyroid dysgenesis. J. Clin. Endocr. Metab. 91: 1428-1433, 2006. [PubMed: 16418214] [Full Text: https://doi.org/10.1210/jc.2005-1350]
Erickson, R. P. Somatic gene mutation and human disease other than cancer. Mutat. Res. 543: 125-136, 2003. [PubMed: 12644182] [Full Text: https://doi.org/10.1016/s1383-5742(03)00010-3]
Goldmuntz, E., Geiger, E., Benson, D. W. NKX2.5 mutations in patients with tetralogy of Fallot. Circulation 104: 2565-2568, 2001. [PubMed: 11714651] [Full Text: https://doi.org/10.1161/hc4601.098427]
Gutierrez-Roelens, I., De Roy, L., Ovaert, C., Sluysmans, T., Devriendt, K., Brunner, H. G., Vikkula, M. A novel CSX/NKX2-5 mutation causes autosomal-dominant AV block: are atrial fibrillation and syncopes part of the phenotype? Europ. J. Hum. Genet. 14: 1313-1316, 2006. [PubMed: 16896344] [Full Text: https://doi.org/10.1038/sj.ejhg.5201702]
Habets, P. E. M. H., Moorman, A. F. M., Clout, D. E. W., van Roon, M. A., Lingbeek, M., van Lohuizen, M., Campione, M., Christoffels, V. M. Cooperative action of Tbx2 and Nkx2.5 inhibits ANF expression in the atrioventricular canal: implications for cardiac chamber formation. Genes Dev. 16: 1234-1246, 2002. [PubMed: 12023302] [Full Text: https://doi.org/10.1101/gad.222902]
Himmelbauer, H., Harvey, R. P., Copeland, N. G., Jenkins, N. A., Silver, L. M. High-resolution genetic analysis of a deletion on mouse chromosome 17 extending over the fused, tufted, and homeobox Nkx2-Nkx2-5 loci. Mammalian Genome 5: 814-816, 1994. [PubMed: 7894168] [Full Text: https://doi.org/10.1007/BF00292022]
Hirayama-Yamada, K., Kamisago, M., Akimoto, K., Aotsuka, H., Nakamura, Y., Tomita, H., Furutani, M., Imamura, S., Takao, A., Nakazawa, M., Matsuoka, R. Phenotypes with GATA4 or NKX2.5 mutations in familial atrial septal defect. Am. J. Med. Genet. 135A: 47-52, 2005. [PubMed: 15810002] [Full Text: https://doi.org/10.1002/ajmg.a.30684]
Hiroi, Y., Kudoh, S., Monzen, K., Ikeda, Y., Yazaki, Y., Nagai, R., Komuro, I. Tbx5 associates with Nkx2-5 and synergistically promotes cardiomyocyte differentiation. Nature Genet. 28: 276-280, 2001. [PubMed: 11431700] [Full Text: https://doi.org/10.1038/90123]
Hosoda, T., Komuro, I., Shiojima, I., Hiroi, Y., Harada, M., Murakawa, Y., Hirata, Y., Yazaki, Y. Familial atrial septal defect and atrioventricular conduction disturbance associated with a point mutation in the cardiac homeobox gene CSX/NKX2-5 in a Japanese patient. Jpn. Circ. J. 63: 425-426, 1999. [PubMed: 10943630] [Full Text: https://doi.org/10.1253/jcj.63.425]
Inga, A., Reamon-Buettner, S. M., Borlak, J., Resnick, M. A. Functional dissection of sequence-specific NKX2-5 DNA binding domain mutations associated with human heart septation defects using a yeast-based system. Hum. Molec. Genet. 14: 1965-1975, 2005. [PubMed: 15917268] [Full Text: https://doi.org/10.1093/hmg/ddi202]
Jay, P. Y., Harris, B. S., Maguire, C. T., Buerger, A., Wakimoto, H., Tanaka, M., Kupershmidt, S., Roden, D. M., Schultheiss, T. M., O'Brien, T. X., Gourdie, R. G., Berul, C. I., Izumo, S. Nkx2-5 mutation causes anatomic hypoplasia of the cardiac conduction system. J. Clin. Invest. 113: 1130-1137, 2004. [PubMed: 15085192] [Full Text: https://doi.org/10.1172/JCI19846]
Kasahara, H., Lee, B., Schott, J.-J., Benson, D. W., Seidman, J. G., Seidman, C. E., Izumo, S. Loss of function and inhibitory effects of human CSX/NKX2.5 homeoprotein mutations associated with congenital heart disease. J. Clin. Invest. 106: 299-308, 2000. [PubMed: 10903346] [Full Text: https://doi.org/10.1172/JCI9860]
Komuro, I., Izumo, S. Csx: a murine homeobox-containing gene specifically expressed in the developing heart. Proc. Nat. Acad. Sci. 90: 8145-8149, 1993. [PubMed: 7690144] [Full Text: https://doi.org/10.1073/pnas.90.17.8145]
Koss, M., Bolze, A., Brendolan, A., Saggese, M., Capellini, T. D., Bojilova, E., Boisson, B., Prall, O. W. J., Elliott, D. A., Solloway, M., Lenti, E., Hidaka, C., Chang, C.-P., Mahlaoui, N., Harvey, R. P., Casanova, J.-L., Selleri, L. Congenital asplenia in mice and humans with mutations in a Pbx/Nkx2-5/p15 module. Dev. Cell 22: 913-926, 2012. [PubMed: 22560297] [Full Text: https://doi.org/10.1016/j.devcel.2012.02.009]
Kostrzewa, M., Grady, D. L., Moyzis, R. K., Floter, L., Muller, U. Integration of four genes, a pseudogene, thirty-one STSs, and a highly polymorphic STRP into the 7-10 Mb YAC contig of 5q34-q35. Hum. Genet. 97: 399-403, 1996. [PubMed: 8786091] [Full Text: https://doi.org/10.1007/BF02185781]
Lyons, I., Parsons, L. M., Hartley, L., Li, R., Andrews, J. E., Robb, L., Harvey, R. P. Myogenic and morphogenetic defects in the heart tubes of murine embryos lacking the homeo box gene Nkx2-5. Genes Dev. 9: 1654-1666, 1995. [PubMed: 7628699] [Full Text: https://doi.org/10.1101/gad.9.13.1654]
Mahlaoui, N., Minard-Colin, V., Picard, C., Bolze, A., Ku, C.-L., Tournilhac, O., Gilbert-Dussardier, B., Pautard, B., Durand, P., Devictor, D., Lachassinne, E., Guillois, B., Morin, M., Gouraud, F., Valensi, F., Fischer, A., Puel, A., Abel, L., Bonnet, D., Casanova, J.-L. Isolated congenital asplenia: a French nationwide retrospective survey of 20 cases. J. Pediat. 158: 142-148, 2011. [PubMed: 20846672] [Full Text: https://doi.org/10.1016/j.jpeds.2010.07.027]
McElhinney, D. B., Geiger, E., Blinder, J., Benson, D. W., Goldmuntz, E. NKX2.5 mutations in patients with congenital heart disease. J. Am. Coll. Cardiol. 42: 1650-1655, 2003. [PubMed: 14607454] [Full Text: https://doi.org/10.1016/j.jacc.2003.05.004]
Mommersteeg, M. T. M., Brown, N. A., Prall, O. W. J., de Gier-de Vries, C., Harvey, R. P., Moorman, A. F. M., Christoffels, V. M. Pitx2c and Nkx2-5 are required for the formation and identity of the pulmonary myocardium. Circ. Res. 101: 902-909, 2007. [PubMed: 17823370] [Full Text: https://doi.org/10.1161/CIRCRESAHA.107.161182]
Moskowitz, I. P. G., Kim, J. B., Moore, M. L., Wolf, C. M., Peterson, M. A., Shendure, J., Nobrega, M. A., Yokota, Y., Berul, C., Izumo, S., Seidman, J. G., Seidman, C. E. A molecular pathway including Id2, Tbx5, and Nkx2-5 required for cardiac conduction system development. Cell 129: 1365-1376, 2007. [PubMed: 17604724] [Full Text: https://doi.org/10.1016/j.cell.2007.04.036]
Nimura, K., Ura, K., Shiratori, H., Ikawa, M., Okabe, M., Schwartz, R. J., Kaneda, Y. A histone H3 lysine 36 trimethyltransferase links Nkx2-5 to Wolf-Hirschhorn syndrome. Nature 460: 287-291, 2009. [PubMed: 19483677] [Full Text: https://doi.org/10.1038/nature08086]
Pashmforoush, M., Lu, J. T., Chen, H., St. Amand, T., Kondo, R., Pradervand, S., Evans, S. M., Clark, B., Feramisco, J. R., Giles, W., Ho, S. Y., Benson, D. W., Silberbach, M., Shou, W., Chien, K. R. Nkx2-5 pathways and congenital heart disease: loss of ventricular myocyte lineage specification leads to progressive cardiomyopathy and complete heart block. Cell 117: 373-386, 2004. [PubMed: 15109497] [Full Text: https://doi.org/10.1016/s0092-8674(04)00405-2]
Pauli, R. M., Scheib-Wixted, S., Cripe, L., Izumo, S., Sekhon, G. S. Ventricular noncompaction and distal chromosome 5q deletion. Am. J. Med. Genet. 85: 419-423, 1999. [PubMed: 10398271]
Pease, W. E., Nordenberg, A., Ladda, R. L. Genetic counselling in familial atrial septal defect with prolonged atrio-ventricular conduction. Circulation 53: 759-762, 1976. [PubMed: 1260978] [Full Text: https://doi.org/10.1161/01.cir.53.5.759]
Peng, T., Wang, L., Zhou, S.-F., Li, X. Mutations of the GATA4 and NKX2.5 genes in Chinese pediatric patients with non-familial congenital heart disease. Genetica 138: 1231-1240, 2010. [PubMed: 21110066] [Full Text: https://doi.org/10.1007/s10709-010-9522-4]
Rauch, R., Hofbeck, M., Zweier, C., Koch, A., Zink, S., Trautmann, U., Hoyer, J., Kaulitz, R., Singer, H., Rauch, A. Comprehensive genotype-phenotype analysis in 230 patients with tetralogy of Fallot. J. Med. Genet. 47: 321-331, 2010. [PubMed: 19948535] [Full Text: https://doi.org/10.1136/jmg.2009.070391]
Reamon-Buettner, S. M., Borlak, J. Somatic NKX2-5 mutations as a novel mechanism of disease in complex congenital heart disease. J. Med. Genet. 41: 684-690, 2004. [PubMed: 15342699] [Full Text: https://doi.org/10.1136/jmg.2003.017483]
Reamon-Buettner, S. M., Borlak, J. HEY2 mutations in malformed hearts. Hum. Mutat. 27: 118 only, 2006. Note: Full article online. [PubMed: 16329098] [Full Text: https://doi.org/10.1002/humu.9390]
Schott, J.-J., Benson, D. W., Basson, C. T., Pease, W., Silberbach, G. M., Moak, J. P., Maron, B. J., Seidman, C. E., Seidman, J. G. Congenital heart disease caused by mutations in the transcription factor NKX2-5. Science 281: 108-111, 1998. [PubMed: 9651244] [Full Text: https://doi.org/10.1126/science.281.5373.108]
Schulkey, C. E., Regmi, S. D., Magnan, R. A., Danzo, M. T., Luther, H., Hutchinson, A. K., Panzer, A. A., Grady, M. M., Wilson, D. B., Jay, P. Y. The maternal-age-associated risk of congenital heart disease is modifiable. Nature 520: 230-233, 2015. [PubMed: 25830876] [Full Text: https://doi.org/10.1038/nature14361]
Shiojima, I., Komuro, I., Inazawa, J., Nakahori, Y., Matsushita, I., Abe, T., Nagai, R., Yazaki, Y. Assignment of cardiac homeobox gene CSX to human chromosome 5q34. Genomics 27: 204-206, 1995. [PubMed: 7665173] [Full Text: https://doi.org/10.1006/geno.1995.1027]
Stallmeyer, B., Fenge, H., Nowak-Gottl, U., Schulze-Bahr, E. Mutational spectrum in the cardiac transcription factor gene NKX2.5 (CSX) associated with congenital heart disease. Clin. Genet. 78: 533-540, 2010. [PubMed: 20456451] [Full Text: https://doi.org/10.1111/j.1399-0004.2010.01422.x]
Turbay, D., Wechsler, S. B., Blanchard, K. M., Izumo, S. Molecular cloning, chromosomal mapping, and characterization of the human cardiac-specific homeobox gene hCsx. Molec. Med. 2: 86-96, 1996. [PubMed: 8900537]
Wang, J., Xin, Y.-F., Liu, X.-Y., Liu, Z.-M., Wang, X.-Z., Yang, Y.-Q. A novel NKX2-5 mutation in familial ventricular septal defect. Int. J. Molec. Med. 27: 369-375, 2011. [PubMed: 21165553] [Full Text: https://doi.org/10.3892/ijmm.2010.585]
Watanabe, Y., Benson, D. W., Yano, S., Akagi, T., Yoshino, M., Murray, J. C. Two novel frameshift mutations in NKX2.5 result in novel features including visceral inversus and sinus venosus type ASD. J. Med. Genet. 39: 807-811, 2002. [PubMed: 12414819] [Full Text: https://doi.org/10.1136/jmg.39.11.807]
Yadava, R. S., Frenzel-McCardell, C. D., Yu, Q., Srinivasan, V., Tucker, A. L., Puymirat, J., Thornton, C. A., Prall, O. W., Harvey, R. P., Mahadevan, M. S. RNA toxicity in myotonic muscular dystrophy induces NKX2-5 expression. Nature Genet. 40: 61-68, 2008. [PubMed: 18084293] [Full Text: https://doi.org/10.1038/ng.2007.28]
Youssoufian, H., Pyeritz, R. E. Mechanisms and consequences of somatic mosaicism in humans. Nature Rev. Genet. 3: 748-758, 2002. [PubMed: 12360233] [Full Text: https://doi.org/10.1038/nrg906]