Genotype frequency of Stargardt disease in Labrador Retrievers in Japan

Canine Stargardt disease causes progressive retinal dysfunction leading to late-onset vision impairment and is inherited as an autosomal recessive trait. The causative mutation, c.4176insC in the ABCA4 gene, has been identified in Labrador Retrievers. This study investigated the genotype frequency of this mutation in Labrador Retrievers in Japan, providing the first estimate for this breed population. Genomic DNA from 120 dogs was analyzed by high-resolution melting with real-time PCR. Of these, 65 (54.2%) were homozygous wild types, 51 (42.5%) were heterozygotes, and 4 (3.3%) were homozygous mutants, with a mutant allele frequency of 0.246. The high carrier rate indicates that the mutation is present at a relatively high frequency in the breed population. Genotyping may help identify individual genotypes and reduce the risk of propagation through breeding.