MUC1 gene encodes the polypeptide of a mucin present on the apical surface of the secreting mammary cells during lactation and on the surface of the milk fat globules (Mather, 2000). MUC1 contains a minisatellite region: the sequence, coding for the extracellular protein domain, consists mostly of a motif of 60 bp that in human, cattle and goat is tandemly repeated a variable number of times (VNTR polymorphism), giving rise to molecular variants of different size (Patton et al., 1995)