UCD is now offering updated testing on your A2 samples which were tested prior to the new reporting of the various variants. The cost is $10.00 Instead of the original A1/A1 or A1/A2 or A2/A2 report, you will receive the report with variants.
The next discussion would be. . . . . what value is it to update and know the variants?
I am not sure of the exact date when they began to report the variants, but it has been a while now. I will find out and let you know by the first of the week. Here is the information page from UCD with some explanation of the variants.
Beta Casein – A2 Genotyping
The solids found in cow’s milk are composed of fat, protein, lactose and minerals. Beta-casein is one of six milk proteins and is produced by the CSN2 gene. Fifteen genetic variants of CSN2 are known which cause changes of certain amino acids in the beta-casein protein and alter its properties. Based on the amino acid in position 67 these variants can be classified into 2 groups - A1 and A2. Variants that belong to the A1 group (His67) are A1, B, C, F and G. Variants that belong to the A2 group (Pro67) are A2, A3, H1, H2, I, J, K and L. The levels of bioactive peptide beta-casomorphin 7 (BCM7) produced from the metabolism of beta casein is several-fold higher for variants in the A1 group than in the A2 group. Higher levels of BCM7 have been associated with negative health effects in humans.
The new test offered by the VGL identifies variants within the A1 and A2 groups thus providing a more detailed resolution of the beta casein gene in cattle. Breeders interested in developing herds for human health benefits should focus in selecting against variants of the A1 group (A1-free). Relative to levels of BCM7 production, variants within each group behave similarly but may differ in other properties.
The A2 genotyping test as specified by the A2 Milk Company classifies beta casein only according to the A1 and A2 group designation. The correspondence between the new VGL results and the group designation for common variants detected in cattle are provided below as an example. The same principle applies to other less frequent variants.
Table 1. Correspondence of genotypes between the new VGL test (variant-based) and A2 Milk Company nomenclature (group-based)
The value of knowing the variants might be in reporting obligates. If I have a cow that is actually the A2/A2 variant and a bull that is actually the A2/A2 variant then I can say that the calf is the A2/A2 variant and if someone tested it, they would get actual A2/A2 variant results.
I was relieved to find that all my Dexters tested so far are the actual A2 variant, because it will require less explaining in the future when someone asks for A2. I can simply say "yes, I have A2", and I don't have to explain the variants.