Alternative titles; symbols
HGNC Approved Gene Symbol: IDH3G
Cytogenetic location: Xq28 Genomic coordinates (GRCh38): X:153,785,768-153,794,375 (from NCBI)
IDH3G encodes a subunit of a heterotetrameric enzyme that is located in mitochondria and presumed to play a major role in the oxidative decarboxylation of isocitrate in the tricarboxylic acid cycle (summary by Brenner et al., 1997).
By genomic sequencing and EST database searching, Brenner et al. (1997) assembled a full-length human cDNA for IDH-gamma. Several EST clones indicated differential splicing. Northern blot analysis detected a 1.5-kb transcript in all 8 tissues examined, with highest expression in tissues with increased energy turnover, i.e., heart, skeletal muscle, and brain.
Brenner et al. (1997) determined that the IDH3G gene contains 13 exons and spans approximately 8.7 kb.
Brenner et al. (1997) identified the IDH3G gene in the Xq28 region, approximately 70 kb telomeric to the ABCD1 gene (300371), and adjacent to the TRAP-delta gene (TRAPD; 300090), which they also cloned. The IDH3G and TRAPD genes are arranged in a compact head-to-head manner and transcribed in opposite directions. The nontranscribed intergenic region between them comprises only 133 bp and is embedded in a CpG island. Brenner et al. (1997) concluded that the CpG island functions as a bidirectional promoter to initiate the transcription of both functionally unrelated genes with distinct expression patterns. Brenner et al. (1997) showed that in both rat and mouse, this region of the genome is similarly compact and comprises less than 249 bp in rat and not more than 164 bp in mouse. In both cases this intergenic region is embedded in a CpG island and is highly conserved, with nucleotide identity values ranging from 70.1% between human and rat to 92.6% between mouse and rat.
In a male patient with periventricular heterotopia (300049) and a large duplication of Xq28 reported by Fink et al. (1997), Fox et al. (1998) found that the centromeric boundary of the duplicated segment of Xq28 was base 3377 of the 3,395 bases of intron 1 of the IDH3G gene, approximately 600 kb distal to DXS15.
Brenner, V., Nyakatura, G., Rosenthal, A., Platzer, M. Genomic organization of two novel genes on human Xq28: compact head to head arrangement of IDH-gamma and TRAP-delta is conserved in rat and mouse. Genomics 44: 8-14, 1997. [PubMed: 9286695] [Full Text: https://doi.org/10.1006/geno.1997.4822]
Fink, J. M., Dobyns, W. B., Guerrini, R., Hirsch, B. A. Identification of a duplication of Xq28 associated with bilateral periventricular nodular heterotopia. Am. J. Hum. Genet. 61: 379-387, 1997. [PubMed: 9311743] [Full Text: https://doi.org/10.1086/514863]
Fox, J. W., Lamperti, E. D., Eksioglu, Y. Z., Hong, S. E., Feng, Y., Graham, D. A., Scheffer, I. E., Dobyns, W. B., Hirsch, B. A., Radtke, R. A., Berkovic, S. F., Huttenlocher, P. R., Walsh, C. A. Mutations in filamin 1 prevent migration of cerebral cortical neurons in human periventricular heterotopia. Neuron 21: 1315-1325, 1998. [PubMed: 9883725] [Full Text: https://doi.org/10.1016/s0896-6273(00)80651-0]