Mapping the locus for ocular melanosis in Cairn Terriers

Area of Science:

• Veterinary Genetics
• Ophthalmology
• Canine Disease Research

Background:

• Familial ocular melanosis (OM) is a hereditary condition affecting Cairn Terriers.
• Identifying the genetic basis of OM is crucial for understanding its pathogenesis and developing diagnostic tools.

Purpose of the Study:

• To map the disease locus for familial ocular melanosis (OM) in the Cairn Terrier breed.
• To identify genetic variants associated with OM in Cairn Terriers.

Main Methods:

• Genome-wide association study (GWAS) in 63 affected and 31 control Cairn Terriers.
• Haplotype analysis to narrow down the associated chromosomal region.
• Sequencing of candidate genes and a microRNA within the identified locus.

Main Results:

• A ~9.2 Mb region on chromosome 11 was significantly associated with OM.
• Haplotype analysis refined the critical region to 1.49 Mb.
• 86% of affected dogs carried a risk allele, while 78% of controls had the non-risk allele; however, no unique variants were found in sequenced genes.

Conclusions:

• Familial ocular melanosis in Cairn Terriers maps to a 1.49 Mb region on chromosome 11, explaining 86% of cases.
• A potential second locus may be responsible for the remaining 14% of OM cases.
• The causal genetic variant for OM in Cairn Terriers remains unidentified, necessitating further investigation into disease mechanisms.