Categories: Vision / eye phene

Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 258100 (trait) , 613758 (trait) , 181031 (gene)

Links to MONDO diseases: No links.

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal recessive

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2013

History: This particular form of PRA was first mentioned by Goldstein et al. (2006), who, by judicious matings, showed that even though its clinical sings are very similar to Progressive rod-cone degeneration (prcd) (OMIA 001298-9615) in a wide range of breeds, the Basenji disorder is not allelic to prcd.

Inheritance: The mating results of Goldstein et al. (2006) suggested autosomal recessive inheritance.

Mapping: A GWAS conducted by Goldstein et al. (2013) on 6 affected and 3 control Basenjis, each genotyped with the Illumina HD Canine SNP Chip comprising 173,662 SNPs, implicated regions on chromosomes CFA4, CFA13 and CFA25. Haplotype analysis suggested the CFA25 region as the most likely candidate region. Homozygosity mapping analysis confirmed the CFA25 region as most likely.

Molecular basis: Sequencing of the two candidate genes in this region led Goldstein et al. (2013) to the discovery of the causal mutation as a stop-loss or extensionl base substitution in the SAG gene (encoding S-antigen): a "tyrosine to cysteine transition mutation at position CFA25:47,845,680 (c.1216T>C . . .) that changed the normal stop codon to code for the amino acid arginine, which would result in a deduced addition of 25 amino acids (p.*405Rext*25) to the normal 405 amino acid protein".

Breed: Basenji.

Associated gene: