Genotyping at the CSN1S1 locus by PCR-RFLP and AS-PCR in a Neapolitan goat population

The goat CSN1S1 gene has for many years been an excellent model for demonstrating that most of the variability observed in the αs1-casein content in goat's milk is due to the presence of autosomal alleles at a single structural locus. Until now, about 17 alleles associated to at least four levels of αs1-casein expression in milk have been described at the CSN1S1 locus in the domestic goat (Capra hircus). The great importance of goat αs1-casein polymorphism is due to its qualitative as well as quantitative implications.In the present work five PCR protocols (PCR-RFLPs, AS-PCR) were set up for rapid genotyping of B1, B2*, B3, B4 and C CSN1S1 alleles, until now detectable only by milk electrophoresis. Application of these protocols, together with previously described methods to identify CSN1S1 01, E, M, F, N and A* (CSN1S1 A, G, I, H) alleles, allow us to define, at DNA level, the genetic structure of the autochthonous goat reared in the province of Naples for the highest number of possible alleles at this locus. Monitoring of CSN1S1 variability in the Neapolitan goat population indicates a high frequency of low (F, 0.368) and null (N, 0.227) alleles.