Association of Melanophilin (MLPH) gene polymorphism with coat colour in Rex rabbits

Rex rabbit, with multiple phenotypes and colourful fur, is an interesting model for assessing the effect of coat colour gene mutations on characteristic pigmentation phenotype. Based on previous study, the melanophilin ( MLPH ) gene is a positional candidate gene related coat colour dilution. The fur colours are a lighter shade, e.g. grey instead of black. We sequenced 1689 base pairs of the MLPH gene in Chinchilla and black Rex rabbit. A total of 13 polymorphisms were identified, including seven missense mutations. The rabbit MLPH gene has a very high GC content and the protein shows 64.87% identity to the orthologous human protein (lack of homologous amino acids encoded by human MLPH exon 9). Hardy-Weinberg test showed that, except for the g.606C>A single nucleotid polymorphism (SNP), all other SNPs were in Hardy-Weinberg equilibrium. Haplotype analysis revealed that the seven missense mutation SNPs of two strains of Rex rabbits formed 10 haplotypes, but there were only seven major types of haplotypes (haplotype frequency P >0.05). The major haplotypes of the Chinchilla and black Rex rabbits were H1/H2/H3/H4/H5 and H1/H2/H3/H6/H8, respectively. The special haplotypes of Chinchilla Rex rabbit (H4, H5, H7) were consistently associated with the Chinchilla phenotype. This study provides evidence that different coat colour formation may be caused by one or more mutations within MLPH gene in several Rex rabbit strains. The data on polymorphisms that are associated with the Chinchilla phenotype facilitate the breeding of rabbits with defined coat colours.