Lack of association between the coding region of the ASIP gene and coat color in donkeys

Coat color is an economically and culturally important trait in Pêga donkeys, influencing breed qualification, competitive categorization, and market value. Despite its relevance, the genetic mechanisms underlying coat color variation in this breed remain poorly understood. Among pigmentation genes, ASIP is a strong candidate due to its known role in mammalian coloration and reported associations with the light points phenotype in donkeys. This study aimed to characterize the coding region of the ASIP gene and investigate its possible association with coat color variation in Pêga donkeys. Twenty animals representing the full spectrum of coat colors accepted for breed registration were sampled. Genomic DNA was extracted from hair follicles, and the three coding exons of ASIP were amplified using previously validated primers. PCR products were purified and sequenced, and resulting sequences were aligned to the donkey reference genome for variant identification. No polymorphisms were detected within the analyzed exons, demonstrating monomorphism across individuals with distinct phenotypes. All animals carried the TT genotype for the previously reported SNP c.349T>C, consistent with the light points phenotype observed in the study population. These findings indicate that the coding region of ASIP does not contribute to the coat color variation documented in the Pêga donkey. The absence of variation suggests that regulatory or noncoding regions of ASIP , as well as additional genomic loci, may underlie pigmentation differences. Further studies incorporating genome-wide strategies are needed to clarify the genetic architecture of coat color in Pêga donkeys and to identify mechanisms responsible for the phenotypic diversity observed.