Describing variability in the tyrosinase (TYR) gene, the albino coat colour locus, in domestic and wild European rabbits

Abstract

Disrupting mutations affecting the tyrosinase (TYR) gene cause different forms of albinism in mice, humans and several other mammals. Classical genetic studies have already reported five alleles at the European rabbit Albino locus, indicated to be part of the C series, each of them with different actions on pheomelanin and eumelanin production, as well as on the eye colour. A few of these alleles have been already characterised at the DNA level by sequencing the coding region of the TYR gene in few rabbit breeds or strains with specific alleles at this locus. In this study, we further characterised the TYR gene by sequencing all coding and flanking regions in a total of 25 rabbits from 11 domestic breeds (Belgian Hare, Burgundy Fawn, Californian, Champagne d’Argent, Giant Chinchilla, Giant Grey, Havana, Leprino di Viterbo, New Zealand White, Silver and White Vienna) and in 11 wild rabbits from Sardinia. Sequencing data identified a total of 15 polymorphisms. We confirmed five missense mutations already detected by other authors, three of which associated with different coat colour phenotypes: p.T373K determining the albino allele; p.E294G causing the Himalayan and the chinchilla alleles; p.T358I observed only in Chinchilla rabbits. In addition to seven other synonymous mutations and one polymorphism in the 3’-untranslated region, two novel missense mutations were identified (p.T144S and p.K224T, the latest was detected only in wild rabbits). This study further contributed to disclose variability in the rabbit TYR gene and confirmed the effects on coat colours of missense mutations. Highlights Mutations in the tyrosinase (TYR) gene cause several coat colour alleles at the Albino locus in mammals. The TYR gene was sequenced in 11 domestic rabbit breeds and in a wild rabbit population. Fifteen single nucleotide polymorphisms (SNPs) were identified: seven were missense mutations. In silico analyses and information already available predicted the effects of some SNPs on coat colour. This study further contributed to disclose variability in the rabbit TYR gene.