A composite six bp in-frame deletion in the melanocortin 1 receptor (MC1R) gene is associated with the Japanese brindling coat colour in rabbits (Oryctolagus cuniculus)

In the domestic rabbit (Oryctolagus cuniculus), classical genetic studies have identified five alleles at the Extension locus: E D (dominant black), E S (steel, weaker version of E D ), E (wild type, normal extension of black), e J (Japanese brindling, mosaic distribution of black and yellow) and e (non-extension of black, yellow/red with white belly). Sequencing almost the complete coding sequence (CDS) of the rabbit MC1R gene, we recently identified two in-frame deletions associated with dominant black (c.280_285del6; alleles E D or E S ) and recessive red (c.304_333del30; allele e) coat colours. It remained to characterize the e J allele whose phenotypic effect is similar to the Orange and Sex-linked yellow loci of cat and Syrian hamster.