Categories: Vision / eye phene

Mendelian trait/disorder: yes

Mode of inheritance: X-linked

Disease-related: yes

Key variant known: no

History: Kaukonen et al. (2020) described two types of PRA in the Miniature Schnauzer breed, the first characterised by "severe PRA findings including total blindness before the age of five years" and named type 1 (see OMIA 002252-9615), and the second characterised by "milder symptoms, slower progression with some visual capacity left at the time of examination and an average age of onset seven years" (named type 2; this entry).

Mapping: Kaukonen et al. (2020) reported that a GWAS of "type 2 cases (n = 6) and controls (n = 33) suggested an association to chromosome X (praw = 7.06x10-7, pgenome = 0.17, λ = 1.19), compatible with the suggested X-chromosomal sex pattern. In this locus, three of the six affected dogs shared a homo- or hemizygous haplotype block of 15.4 Mb from 38,294,920 bp to 53,726,107 bp that was absent in the controls and the rest of the type 2 cases (Fig 3C and 3D). As the number of type 2 cases was small, replication of the GWAS result in chromosome X in a larger sample cohort is needed to confirm the locus before further genetic analyses are performed. RPGR, the known canine PRA gene in CFAX, is not located in the preliminary locus".

Breed: Miniature Schnauzer (Dog) (VBO_0200896).
Breeds in which the phene has been documented. (If a likely causal variant has been documented for the phene, see the variant table breeds in which the variant has been reported).