An SNP in the goat CSN2 promoter region is associated with the absence of beta-casein in milk.

So far, at least eight alleles in the goat CSN2 locus have been associated with different levels of beta-casein expression in milk. Alleles CSN2(A), CSN2(A1), CSN2(B), CSN2(C), CSN2(D) and CSN2(E) have been associated with normal content (allele effects of about 5 g of beta-casein per litre), whereas the CSN2(0) and CSN2(01) alleles have been associated with non-detectable levels of beta-casein. Analysis of the coagulation properties of milk with and without beta-casein demonstrates that milk without beta-casein shows longer coagulation times (about three times the normal value, 15-25 min vs 4-7 min) and low curd firmness (so low that it is impossible to measure). Most of these alleles have been characterized genetically. Herein, we report the identification of a previously unreported SNP in the goat CSN2 promoter region (AJ011018:g.1311T>C), which is associated with the absence of beta-casein in the milk. Given the absence of the beta-casein in animals with this allele, it is possible that this mutation is involved in gene regulation processes. It is also possible that this allele is in linkage disequilibrium with a causative mutation for lack of expression. Sequencing of the complete genomic region of the CSN2 gene in these animals is needed. Finally, we developed a PCR-based method that allows detection of this mutation.