Heritability of lenticular myopia in English Springer spaniels.
OBJECTIVE
We determined whether naturally-occurring lenticular myopia in English Springer spaniels (ESS) has a genetic component.


METHODS
Streak retinoscopy was performed on 226 related ESS 30 minutes after the onset of pharmacologic mydriasis and cycloplegia. A pedigree was constructed to determine relationships between affected offspring and parents. Estimation of heritability was done in a Bayesian analysis (facilitated by the MCMCglmm package of R) of refractive error in a model, including terms for sex and coat color. Myopia was defined as ≤-0.5 diopters (D) spherical equivalent.


RESULTS
The median refractive error for ESS was 0.25 D (range, -3.5 to +4.5 D). Median age was 0.2 years (range, 0.1-15 years). The prevalence of myopia in related ESS was 19% (42/226). The ESS had a strong correlation (r = 0.95) for refractive error between the two eyes. Moderate heritability was present for refractive error with a mean value of 0.29 (95% highest probability density, 0.07-0.50).


CONCLUSIONS
The distribution of refractive error, and subsequently lenticular myopia, has a moderate genetic component in ESS. Further investigation of genes responsible for regulation of the development of refractive ocular components in canines is warranted.
Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois.
Melissa A
MA
Kubai
Amber L
AL
Labelle
Ralph E
RE
Hamor
Donald O
DO
Mutti
Thomas R
TR
Famula
Christopher J
CJ
Murphy
D000818:Animals; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs; D008390:Markov Chains; D009216:Myopia / Q000235:genetics* / Q000662:veterinary*; D010375:Pedigree; D010641:Phenotype; D019655:Quantitative Trait, Heritable; D012030:Refractive Errors / Q000235:genetics / Q000662:veterinary; D013045:Species Specificity
English Springer spaniel; heritability; lenticular myopia; refractive error