SNOMEDCT: 722057000; ORPHA: 370091; DO: 0070099;
Cytogenetic location: 4q24 Genomic coordinates (GRCh38) : 4:100,100,001-106,700,000
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 4q24 | Albinism, oculocutaneous, type V | 615312 | Autosomal recessive | 2 |
Oculocutaneous albinism is a genetically heterogeneous disorder manifested as a loss of pigmentation in the eyes, skin, and hair (summary by Kausar et al., 2013).
For a general phenotypic description and a discussion of genetic heterogeneity of oculocutaneous albinism, see OCA1 (203100).
Kausar et al. (2013) reported a consanguineous Pakistani family (PKAB80) in which 6 members had golden-colored hair, white skin, nystagmus, photophobia, foveal hypoplasia, and impaired visual acuity. Physical, clinical, and hematologic evaluations of affected individuals revealed no other obvious clinical phenotypes.
Kausar et al. (2013) performed genomewide linkage analysis in a consanguineous Pakistani family segregating nonsyndromic oculocutaneous albinism and found evidence suggestive of linkage only to SNPs on chromosomes 4 and 14. Genotyping of short tandem repeat markers or SNPS on both chromosomes showed linkage only with 4q24 markers. Haplotype analysis revealed a 1.06-cM interval of homozygosity. A maximum 2-point lod score (theta = 0) was obtained for marker D4S961. The linkage interval of the locus, which the authors designated OCA5, spanned approximately 3.84 Mb and contained 14 genes. The authors screened the coding exons and flanking intronic sequences of 9 of these genes, but identified no mutations.
Based on a consensus of the albinism research community (Montoliu et al., 2013), the form of oculocutaneous albinism mapped to chromosome 4q24 is here designated OCA5.
Kausar, T., Bhatti, M. A., Ali, M., Shaikh, R. S., Ahmed, Z. M. OCA5, a novel locus for non-syndromic oculocutaneous albinism, maps to chromosome 4q24. (Letter) Clin. Genet. 84: 91-93, 2013. [PubMed: 23050561] [Full Text: https://doi.org/10.1111/cge.12019]
Montoliu, L., Gronskov, K., Wei, A.-H., Martinez-Garcia, M., Fernandez, A., Arveiler, B., Morice-Picard, F., Riazuddin, S., Suzuki, T., Ahmed, Z. M., Rosenberg, T., Li, W. Increasing the complexity: new genes and new types of albinism. Pigment Cell Melanoma Res. 27: 11-18, 2013. [PubMed: 24066960] [Full Text: https://doi.org/10.1111/pcmr.12167]