Coat colours in the Massese sheep breed are associated with mutations in the agouti signalling protein (ASIP) and melanocortin 1 receptor (MC1R) genes

L. Fontanesi, S. Dall'Olio, F. Beretti, B. Portolano, V. Russo
2010 Animal  
Massese is an Italian dairy sheep breed characterized by animals with black skin and horns and black or apparent grey hairs. Owing to the presence of these two coat colour types, this breed can be considered an interesting model to evaluate the effects of coat colour gene polymorphisms on this phenotypic trait. Two main loci have been already shown to affect coat colour in sheep:AgoutiandExtensioncoding for the agouti signalling protein (ASIP) and melanocortin 1 receptor (MC1R) genes,
more » ... ly. TheAgoutilocus is affected by a large duplication including theASIPgene that may determine theAgoutiwhite and tan allele (AWt). Other disrupting or partially inactivating mutations have been identified in exon 2 (a deletion of 5 bp, D5; and a deletion of 9 bp, D9) and in exon 4 (g.5172T>A, p.C126S) of theASIPgene. Three missense mutations in the sheepMC1Rgene cause the dominant blackEDallele (p.M73K and p.D121N) and the putative recessiveeallele (p.R67C). Here, we analysed theseASIPandMC1Rmutations in 161 Massese sheep collected from four flocks. The presence of one duplicated copy allele including theASIPgene was associated with grey coat colour (P= 9.4E-30). Almost all animals with a duplicated copy allele (37 out of 41) showed uniform apparent grey hair and almost all animals without a duplicated allele (117 out of 120) were completely black. Different forms of duplicated alleles were identified in Massese sheep including, in almost all cases, copies with exon 2 disrupting or partially inactivating mutations making these alleles different from theAWtallele. A few exceptions were observed in the association betweenASIPpolymorphisms and coat colour: three grey sheep did not carry any duplicated copy allele and four black animals carried a duplicated copy allele. Of the latter four sheep, two carried theEDallele of theMC1Rgene that may be the cause of their black coat colour. The coat colour of all other black animals may be determined by non-functionalASIPalleles (non-agouti alleles,Aa) and in a few cases by theEDExtensionallele. At least three frequentASIPhaplotypes ([D5:g.5172T], [N:g.5172A] and [D5:g.5172A]) were detected (organized into six different diplotypes). In conclusion, the results indicated that coat colours in the Massese sheep breed are mainly derived by combiningASIPandMC1Rmutations.
doi:10.1017/s1751731110001382 pmid:22440696 fatcat:cmin6bkzrfedllvqhjatkvquoe