IDENTIFICATION AND ANALYSIS OF SINGLE NUCLEOTIDE POLYMORPHISMS IN THE MYOSIN VA (MYO5A) GENE AND ITS EXCLUSION AS THE CAUSATIVE GENE OF THE DILUTE COAT COLOUR LOCUS IN RABBIT

Classical genetic studies have identified different coat colour loci in rabbit and comparative analyses have established corresponding loci across species. In particular, the rabbit dilute locus is determined by a recessive coat colour mutation that modifies the basic colours influenced by the agouti and extension mutations. In mice, similar phenotypic effects are determined by a similarly named locus. This locus encodes the myosin VA (Myo5a) gene, whose protein product is an unconventional myosin that plays an essential role in melanosome transport in the melanocytes. We selected the same gene as a strong candidate for explaining the dilute coat colour in rabbit. To this end, 1399 bp were re-sequenced, spanning 4 exons out of 41 exons and portions of intronic regions of the rabbit MYO5A gene to identify polymorphisms that could be useful to confirm or exclude this gene as causative of the rabbit dilute locus. Nine polymorphisms were identified, one of which was used to follow the segregation of the blue and black colours in a Checkered Giant F1 family. The single nucleotide polymorphism (SNP) analysed did not co-segregate with the 2 colours. These results excluded the MYO5A gene as determinant of the dilute locus in rabbit. The 2 alleles of this SNP were also present in several other breeds with different coat colours, further indicating that this marker is not associated with the dilute mutation in rabbits. Other candidates should be investigated to identify the causative gene of this locus in rabbit.