Categories: Vision / eye phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 300839 (gene) , 312700 (trait)

Links to relevant human diseases in MONDO:

• MONDO:0010725: X-linked retinoschisis

Single-gene trait/disorder: yes

Mode of inheritance: X-linked

Disease-related: yes

Key variant known: yes

Year key variant first reported: 2026

Species-specific name: PRA

Molecular basis: Vähämäki et al. (2026) conducted whole genome sequencing of a Pomeranian with progressive retinal atrophy and identified "an X-chromosomal hemizygous 1-bp duplication, predicted to result in frameshift and stoploss in the RS1 gene: c.442dupC, p.(R148Pfs*45) (XM_038586978.1, XP_038442906.1) [omia.variant:1954]" as likley causal variant. " Genotypes from altogether 162,919 dogs ... 
across breeds identified one homozygous, 10 hemizygous and 11 heterozygous dogs (all 22 dogs Pomeranians or Pomeranian-mixes), while the rest 162,897 tested dogs were wild type ... . The results indicate the c.442dupC is likely a rare Pomeranian-specific variant. Unfortunately, no additional information was available from the hemi- and homozygous animals, and thus the variant’s clinical consequences remain to be confirmed."

Clinical features: Vähämäki et al. (2026) report an 11 year old Pomeranian with progressive retinal atrophy (PRA). Spectral-domain optical coherence tomography confirmed severe thinning of the total retina and identified a complete loss of the photoreceptor layer.

Breed: Pomeranian (Dog) (VBO_0201043).
Breeds in which the phene or likely causal variants have been documented. If a likely causal variant has been documented, see variant-specific breed information in the variant table. (Breed information may be incomplete).

Associated gene: