Depigmentation of skin and hair color in the somatic cell cloned pig.

Previously, we have successfully produced nine cloned piglets using Duroc donor cells. Among these clones, one showed distinct depigmentation of the skin and hair color during puberty. In this study, we selected a clone with depigmentation to investigate the etiology of the anomaly in somatic cell nuclear transfer. We hypothesized that genes related to Waardenburg syndrome (Mitf, Pax-3, Sox-10, Slug, and Kit) are closely associated with the depigmentation of pig, which was derived from somatic cell nuclear transfer (scNT). Total RNA was extracted from the ear tissue of affected and unaffected scNT-derived pigs, and the transcripts encoding Mitf, Pax-3, Sox-10, and Slug, together with the Kit gene, were amplified by reverse transcription-polymerase chain reaction, sequenced, and analyzed. The cDNA sequences from the scNT pig that showed progressive depigmentation did not reveal a mutation in these genes. Although we did not find any mutations in these genes, expression of the genes implicated in Waardenburg syndrome was severely down-regulated in the affected scNT pig when compared with unaffected scNT pigs. This down-regulation of gene expression may result in a previously undescribed phenotype that shows melanocyte instability, leading to progressive loss of pigmentation.