The occurrence of genetic polymorphism and related non‐allelic proteins increases the compositional complexity of goat α (s1) ‐ CN

A genetic survey on three autochthonous goat breeds reared in Italy was carried out by a proteomic approach. This methodology, further to providing the phenotypic frequency of identified α s1 genetic variants, allowed to determine (i) the additional constitutive presence of a non‐allelic ‘α s1 ‐ casein (CN) F like’ protein in goat ‘strong’ α s1 variants; (ii) an α s1 ‐ CN B 2 like protein, expressed at very low quantitative level, in goat ‘weak’ α s1 ‐ CN variants, and, as main focus; (iii) the occurrence of a new α s1 ‐ CN D 1 variant characterised by the lack of α s1 (f59‐69) sequence otherwise encoded by exon 9 in goat α s1 B 2 reference. The same exon skipping event had been identified since 1990, as responsible of the ‘weak quantitative class’ of α s1 ‐ CN D variant (0.6 g/L), while the new α s1 ‐ CN D 1, has been ‘quantitatively’ classified as an ‘intermediate’ variant, since 1.8 g/L per allele was assessed in the milk.