Complex segregation analysis of deafness in Dalmatians

Objective-To use pedigree analysis to evaluate the feasibility of a major l ocus model for deafness in Dalmatians. Animals-605 purebred Dalmations from 42 families. Procedure-Hearing loss was evaluated through the brainstem auditory-evoked response. Dogs were classified into mutually exclusive categories: normal h earing, unilaterally deaf, or bilaterally deaf. Information was collected o n sex, coat color, presence or absence of a color patch at birth, and eye c olor. Statistical analyses were performed by use of regressive logistic mod els designed for complex segregation analysis. Genetic correlations among e ye color, deafness, and color patch were estimated. Results-Prevalence of hearing loss was 11% for dogs classified as unilatera lly deaf and 5% for dogs that were bilaterally deaf. Complex segregation an alysis detected statistical evidence of a single allele with an expected fr equency of 0.21 that had an effect on the prevalence of deafness. Results o f analyses suggested that this locus cannot completely explain the inherita nce and incidence of deafness in Dalmatians. Genetic correlation estimates among deafness, eye color, and color patch revealed strong interrelation-sh ips among these characteristics. Conclusions and Clinical Relevance-To reduce the incidence of hearing loss in Dalmatians, unilaterally deaf, blue-eyed dogs should not be considered a s potential parents.