Identification of new alleles at the KIT locus in Nero Siciliano pigs.

Coat colour phenotypes in European pig breeds are mainly due to alleles at the Extension and Dominant White loci. At the latter locus, several alleles are caused by mutations in the v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) gene that are mainly originated by a combination of gene duplication and single nucleotide polymorphisms. Nero Siciliano is one of the few survived local Italian pig breed reared in the Nebrodi mountains of the island of Sicily The animals are usually completely black but a few show white portions mainly in the face or in the fore legs. In order to identify the genetic factors determining the presence of white portions, we genotyped 97 Nero Siciliano pigs (25 with white portions) for the splice site mutation of the intron 17 of the KIT gene that cause the Dominant White I allele. These animals were also analysed for the presence of the duplication of the same gene. None of the pigs carried the splice site mutation while 7 out of 25 animals with white portions were positive for the duplication test, suggesting that other alleles at this locus or other genes might affect this phenotype in Nero Siciliano pigs. Then, 8 of the 21 exons of the KIT gene were sequenced in eight Nero Siciliano pigs with different colour phenotypes. Several mutations were identified indicating that new alleles of the KIT gene are present in this breed. Further studies are under way to sequence all exons and evaluate the effect on coat colour of the identified mutations.