Alternative titles; symbols
HGNC Approved Gene Symbol: CFHR1
Cytogenetic location: 1q31.3 Genomic coordinates (GRCh38): 1:196,819,731-196,832,189 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 1q31.3 | {Hemolytic uremic syndrome, atypical, susceptibility to} | 235400 | Autosomal dominant; Autosomal recessive | 3 |
| {Macular degeneration, age-related, reduced risk of} | 603075 | Autosomal dominant | 3 |
Timmann et al. (1991) isolated 2 differently glycosylated forms of a human serum protein antigenically related to complement factor H (CFH; 134370). Skerka et al. (1991) isolated a cDNA clone for this protein that predicted a protein sequence of 327 amino acids with a leader sequence. The secreted part of the protein comprised 5 tandem repeating units, termed short consensus repeats (SCRs). The 3-prime end showed sequence homology to the 3-prime end of human complement factor H. Skerka et al. (1991) also isolated a cDNA clone that appeared to represent a transcribed pseudogene, since it contained a stop codon (TAA) within SCR 1.
See also Zipfel and Skerka (1994).
Gross (2014) mapped the CFHR1 gene to chromosome 1q31.3 based on an alignment of the CFHR1 sequence (GenBank BC107771) with the genomic sequence (GRCh37).
By immunoprecipitation and immunoblot analyses, Kunert et al. (2007) found that factor H, via SCR domains 6 to 7 and 19 to 20, and FHR1, via SCR domains 3 to 5, bound to surface-expressed Pseudomonas aeruginosa elongation factor Tuf and also to recombinant Tuf. Factor H and plasminogen (PLG; 173350) bound simultaneously to Tuf, and PLG was proteolytically activated. Plasma without factor H did not support P. aeruginosa survival, and survival increased in a factor H dose-dependent manner. Kunert et al. (2007) proposed that Tuf acts as a virulence factor by acquiring host proteins to the pathogen surface, controlling complement, and possibly facilitating tissue invasion.
Feifel et al. (1992) and Meyer et al. (1995) described polymorphisms of the factor H-related gene.
Hughes et al. (2006) found that a haplotype carrying an 84-kb deletion of the CFHR1 and CFHR3 (605336) genes (134371.0001) was associated with a decreased risk of age-related macular degeneration (see ARMD1, 603075). The authors did not assess the relative importance of the deletion of CFHR1 and CFHR3 in contributing to the protective nature of the haplotype; however, they noted that the products of both genes are present in the circulation, where they have the potential to compete with CFH for C3 (120700) binding. Hughes et al. (2006) hypothesized that CFH produced from full-length transcript is beneficial and that other CFH-related proteins interfere with regulation of complement activity.
Extending their previous work (see Hughes et al., 2006), Zipfel et al. (2007) found that the 84-kb CFHR1/CFHR3 deletion was associated with an increased risk of atypical hemolytic-uremic syndrome (aHUS; 235400) in 2 independent European cohorts. Zipfel et al. (2007) noted that the present study showed an opposite effect for the variant from that of Hughes et al. (2006), which may be due to a disease-modifying action of the deletion or linkage disequilibrium between the deletion and other susceptibility alleles. Of 147 patients with aHUS, 121 of whom had previously been reported by Zipfel et al. (2007), Jozsi et al. (2008) identified serum anti-CFH autoantibodies in 16 (11%); 14 lacked CFHR1/CFHR3 completely and 2 showed extremely low CFHR1/CFHR3 plasma levels. The findings illustrated a new combination of 2 susceptibility factors for the development of aHUS.
In 711 individuals with ARMD and 1,041 controls, Raychaudhuri et al. (2010) reproduced associations at the Y402H allele (134370.0008), using rs10801555 as a proxy, and rs1410996 (134370.0016), using rs10737680 as a proxy, but observed modest evidence for association with the CFHR1/CFHR3 deletion (p = 7.0 x 10(-21)). Logistic regression conditioned on rs10737680 resulted in substantially mitigated statistical strength for the protective effect of the CFHR1/CFHR3 deletion, suggesting that the CFHR1/CFHR3 deletion and rs10737680 were not entirely independent. Haplotype analysis demonstrated that both markers tag a collection of low-risk haplotypes, but neither tags all of them perfectly, suggesting that there could be 1 or more not-yet-identified variants that better explain disease risk. Raychaudhuri et al. (2010) favored the parsimonious explanations of a single functional allele in high correlation with rs10737680 acting on all protective haplotypes or of a risk variant acting on the intermediate risk haplotypes. In response, Hughes et al. (2010) noted that the finding of a lower statistical significance for the CFHR1/CFHR3 deletion than for rs10801555 or rs10737680 was a reflection of allele frequencies rather than effect size. The authors suggested that parsimonious explanations with the fewest functional elements are unnecessarily restrictive and noted that functional studies support a minimum of 3 factors.
The human factor H protein family consists of 7 related plasma proteins: factor H (CFH); factor H-like protein-1 (CFHL1), which is a splicing isoform of CFH; and 5 factor H-related proteins: CFHR1, CFHR2 (600889), CFHR3, CFHR4 (605337), and CFHR5 (608593). All members of this protein family share structural similarities. They represent secreted plasma proteins, are exclusively composed of conserved protein domains termed complement control protein modules (CCPs), are synthesized primarily by hepatocytes, and are immunologically related to each other and the factor H (Zipfel et al., 1999). All CFH-related proteins are encoded by separate genes that, like the CFH gene, are located in the regulators of complement activation (RCA) gene cluster on chromosome 1q31-q32.1 (Diaz-Guillen et al., 1999; Jozsi et al., 2005).
Hughes et al. (2006) identified an 84-kb deletion that occurred between 2 virtually identical 29-kb segments of duplication and was located downstream of the CFH gene and upstream of the CFHR4 gene. By sequence analysis in 3 individuals who were homozygous for the deletion, Zipfel et al. (2007) showed that the deletion resulted from nonallelic homologous recombination.
Hughes et al. (2006) genotyped polymorphisms spanning the cluster of CFH and 5 CFH-related genes on chromosome 1q23 in 173 individuals with severe neovascular age-related macular degeneration (ARMD; see 603075) and 170 elderly controls with no signs of ARMD. They found that a haplotype carrying the CFHR1/CFHR3 deletion genes was associated with decreased risk of ARMD, being present on 20% of chromosomes of controls and 8% of chromosomes of individuals with ARMD. The proteins encoded by these genes were absent in serum of homozygotes. The protective effect of the deletion haplotype could not be attributed to linkage disequilibrium with the CFH Y402H variant (134370.0008) and was replicated in an independent sample.
Extending their previous work (see Hughes et al., 2006), Zipfel et al. (2007) found that the CFHR1/CFHR3 deletion was associated with an increased risk of atypical hemolytic-uremic syndrome (aHUS; 235400) in 2 independent European cohorts. In the first group, 19 (16%) of 121 aHUS patients had the deletion compared to 2 of 100 control individuals. Three of the patients had a homozygous deletion. All patients had normal serum factor H levels. In the second group comprising 66 patients, 28% had the deletion compared to 6% of controls. Ten percent and 2% of patients and controls, respectively, were homozygous for the deletion. In vitro functional expression studies showed that CFHR1/CFHR3-deficient plasma had decreased protective activity against erythrocyte lysis, suggesting a defective regulation of complement activation. Zipfel et al. (2007) noted that the present study showed an opposite effect for the variant from that of Hughes et al. (2006), which may be due to a disease-modifying action of the deletion or linkage disequilibrium between the deletion and other susceptibility alleles. Of 147 patients with aHUS, 121 of whom had previously been reported by Zipfel et al. (2007), Jozsi et al. (2008) identified serum anti-CFH autoantibodies in 16 (11%); 14 lacked CFHR1/CFHR3 completely and 2 showed extremely low CFHR1/CFHR3 plasma levels. The findings illustrated a new combination of 2 susceptibility factors for the development of aHUS.
The CFHR1/CFHR3 deletion exclusively occurs on one of the 2 protective CFH haplotypes, both of which are tagged by the protective allele of single-nucleotide polymorphism rs2274700 (A473A). In a German cohort of 530 ARMD patients, Fritsche et al. (2010) showed that protection against ARMD conferred by delta-CFHR3/CFHR1 was independent of the effects of CFH polymorphisms rs2274700 and rs1061170 (Y402H; 134370.0008). This suggested a functional role of CFHR1 and/or CFHR3 in disease pathogenesis. Fritsche et al. (2010) determined that CFHR3 is a novel human complement regulator that inhibits C3 (120700) convertase activity. CFHR3 displayed antiinflammatory effects by blocking C5A (see 120900) generation and C5A-mediated chemoattraction of neutrophils. In addition, CFHR3 and CFHR1 competed with factor H for binding to the central complement component C3. Thus, deficiency of CFHR3 and CFHR1 resulted in a loss of complement control but enhanced local regulation by factor H. Fritsche et al. (2010) hypothesized that dysregulation of complement may play a central role in ARMD pathology.
Diaz-Guillen, M. A., Rodriguez de Cordoba, S., Heine-Suner, D. A radiation hybrid map of complement factor H and factor H-related genes. Immunogenetics 49: 549-552, 1999. [PubMed: 10380701] [Full Text: https://doi.org/10.1007/s002510050534]
Feifel, E., Prodinger, W. M., Molgg, M., Schwaeble, W., Schonitzer, D., Koistinen, V., Misasi, R., Dierich, M. P. Polymorphism and deficiency of human factor H-related proteins p39 and p37. Immunogenetics 36: 104-109, 1992. [PubMed: 1535336] [Full Text: https://doi.org/10.1007/BF00215286]
Fritsche, L. G., Lauer, N., Hartmann, A., Stippa, S., Keilhauer, C. N., Oppermann, M., Pandey, M. J., Kohl, J., Zipfel, P. F., Weber, B. H. F., Skerka, C. An imbalance of human complement regulatory proteins CFHR1, CFHR3 and factor H influences risk for age-related macular degeneration (AMD). Hum. Molec. Genet. 19: 4694-4704, 2010. [PubMed: 20843825] [Full Text: https://doi.org/10.1093/hmg/ddq399]
Gross, M. B. Personal Communication. Baltimore, Md. 6/27/2014.
Hughes, A. E., Orr, N., Cordell, H. J., Goodship, T. Hughes et al. reply. (Letter) Nature Genet. 42: 555-556, 2010.
Hughes, A. E., Orr, N., Esfandiary, H., Diaz-Torres, M., Goodship T., Chakravarthy, U. A common CFH haplotype, with deletion of CFHR1 and CFHR3, is associated with lower risk of age-related macular degeneration. Nature Genet. 38: 1173-1177, 2006. Note: Erratum: Nature Genet. 39: 567 only, 2007. [PubMed: 16998489] [Full Text: https://doi.org/10.1038/ng1890]
Jozsi, M., Licht, C., Strobel, S., Zipfel, S. L. H., Richter, H., Heinen, S., Zipfel, P. F., Skerka, C. Factor H autoantibodies in atypical hemolytic uremic syndrome correlate with CFHR1/CFHR3 deficiency. Blood 111: 1512-1514, 2008. [PubMed: 18006700] [Full Text: https://doi.org/10.1182/blood-2007-09-109876]
Jozsi, M., Richter, H., Loschmann, I., Skerka, C., Buck, F., Beisiegel, U., Erdei, A., Zipfel, P. F. FHR-4A: a new factor H-related protein is encoded by the human FHR-4 gene. Europ. J. Hum. Genet. 13: 321-329, 2005. [PubMed: 15562282] [Full Text: https://doi.org/10.1038/sj.ejhg.5201324]
Kunert, A., Losse, J., Gruszin, C., Huhn, M., Kaendler, K., Mikkat, S., Volke, D., Hoffmann, R., Jokiranta, T. S., Seeberger, H., Moellmann, U., Hellwage, J., Zipfel, P. F. Immune evasion of the human pathogen Pseudomonas aeruginosa: elongation factor Tuf is a factor H and plasminogen binding protein. J. Immun. 179: 2979-2988, 2007. [PubMed: 17709513] [Full Text: https://doi.org/10.4049/jimmunol.179.5.2979]
Meyer, C. G., Skerka, C., Zipfel, P. F. Polymorphism of the human factor H-related gene (FHR-1) and of factor H in a West African individual. Immunogenetics 41: 335 only, 1995. [PubMed: 7721361] [Full Text: https://doi.org/10.1007/BF00172164]
Raychaudhuri, S., Ripke, S., Li, M., Neale, B. M., Fagerness, J., Reynolds, R., Sobrin, L., Swaroop, A., Abecasis, G., Seddon, J. M., Daly, M. J. Associations of CFHR1-CFHR3 deletion and a CFH SNP to age-related macular degeneration are not independent. (Letter) Nature Genet. 42: 553-555, 2010. [PubMed: 20581873] [Full Text: https://doi.org/10.1038/ng0710-553]
Skerka, C., Horstmann, R. D., Zipfel, P. F. Molecular cloning of a human serum protein structurally related to complement factor H. J. Biol. Chem. 266: 12015-12020, 1991. [PubMed: 1711047]
Timmann, C., Leippe, M., Horstmann, R. D. Two major serum components antigenically related to complement factor H are different glycosylation forms of a single protein with no factor H-like complement regulatory functions. J. Immun. 146: 1265-1270, 1991. [PubMed: 1825108]
Zipfel, P. F., Edey, M., Heinen, S., Jozsi, M., Richter, H., Misselwitz, J., Hoppe, B., Routledge, D., Strain, L., Hughes, A. E., Goodship, J. A., Licht, C., Goodship, T. H. J., Skerka, C. Deletion of complement factor H-related genes CFHR1 and CFHR3 is associated with atypical hemolytic uremic syndrome. PLoS Genet. 3: e41, 2007. Note: Electronic Article. [PubMed: 17367211] [Full Text: https://doi.org/10.1371/journal.pgen.0030041]
Zipfel, P. F., Jokiranta, T. S., Hellwage, J., Koistinen, V., Meri S. The factor H protein family. Immunopharmacology 42: 53-60, 1999. [PubMed: 10408366] [Full Text: https://doi.org/10.1016/s0162-3109(99)00015-6]
Zipfel, P. F., Skerka, C. Complement factor H and related proteins: an expanding family of complement-regulatory proteins? Immun. Today 15: 121-126, 1994. [PubMed: 8172644] [Full Text: https://doi.org/10.1016/0167-5699(94)90155-4]