Investigation of the premelanosome protein (PMEL or SILV) gene and identification of polymorphism excluding it as the determinant of the dilute locus in domestic rabbits (Oryctolagus cuniculus)

After the rediscovery of the Mendel's laws, the domesticated European rabbit (Orycolagus cuniculus) has been the objective of pioneering studies on coat colour genetics. However, despite the early role of this species in defining genetic mechanisms determining this phenotypic trait, only recently a few loci have been characterized at the molecular level analysing also in rabbits genes already shown to affect coat colour in mice. We herein investigated the rabbit premelanosome protein (PMEL) gene, also known as melanocyte protein Pmel 17 (PMEL17) or silver (SILV), as mutations in the homologous gene in mice and other species produce phenotypic effects similar to what is observed in the dilute coat colour in rabbit. The rabbit dilute locus is determined by a recessive coat colour mutation that dilutes the black to blue (grey) interacting with the basic colours influenced by the agouti and extension loci. To investigate this candidate gene, we isolated and sequenced cDNAs as well as portions of intronic and exonic regions of the PMEL gene in several rabbits with different coat colours and identified single nucleotide polymorphisms, including several missense mutations. One polymorphism, positioned in intron 7, was genotyped in a family in which there was segregation of the dilute coat colour. The results excluded PMEL as the causative gene for the dilute locus in rabbits, shortening the list of candidate genes that should be analysed to identify the mutation determining this phenotypic trait.