ORPHA: 49382; DO: 0110010;
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
Gene/Locus |
Gene/Locus MIM number |
|---|---|---|---|---|---|---|
| 1p13.3 | Achromatopsia 4 | 613856 | 3 | GNAT2 | 139340 |
A number sign (#) is used with this entry because achromatopsia-4 can be caused by homozygous or compound heterozygous mutation in the GNAT2 gene (139340) on chromosome 1p13.
Achromatopsia, also referred to as rod monochromacy, is an autosomal recessive ocular disorder characterized by total colorblindness, low visual acuity, photophobia, and nystagmus (Kohl et al., 2002).
For a general description and a discussion of genetic heterogeneity of achromatopsia, see 216900.
Achromatopsia-4 is an autosomal recessive disorder (Kohl et al., 2002).
Kohl et al. (2002) reported 5 families with achromatopsia, with 4 showing homozygosity for protein-truncation mutations in the GNAT2 gene (139340.0001; 139340.0003-139340.0004).
In a consanguineous Pakistani family with achromatopsia-4, Aligianis et al. (2002) used autozygosity mapping and positional candidate gene analysis to identify a 4-bp insertion (842insTCAG) in exon 7 of the GNAT2 gene that segregated with the disease.
Aligianis, I. A., Forshew, T., Johnson, S., Michaelides, M., Johnson, C. A., Trembath, R. C., Hunt, D. M., Moore, A. T., Maher, E. R. Mapping of a novel locus for achromatopsia (ACHM4) to 1p and identification of a germline mutation in the alpha subunit of cone transducin (GNAT2). J. Med. Genet. 39: 656-660, 2002. [PubMed: 12205108] [Full Text: https://doi.org/10.1136/jmg.39.9.656]
Kohl, S., Baumann, B., Rosenberg, T., Kellner, U., Lorenz, B., Vadala, M., Jacobson, S. G., Wissinger, B. Mutations in the cone photoreceptor G-protein alpha-subunit gene GNAT2 in patients with achromatopsia. Am. J. Hum. Genet. 71: 422-425, 2002. [PubMed: 12077706] [Full Text: https://doi.org/10.1086/341835]