At the end of 2016 US Davis developed a more detailed A2 genotyping test. I've seen it cause some confusing amongst A2A2 enthusiasts as they don't understand that an A2/I or I/I test result still means the cow tested is A2/A2.
I contacted US Davis to clarify this with their testing representative and they said: "At this time the more specific information within the A2 test isn't known but that they now are able to start collecting more detailed variant information and eventually this datas information can be studied."
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.
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.
1. If your results say A1/F, this would have been identified as an A1/A1 cow under the old test.
2. If your results are J/K, this would have been identified as an A2/A2 cow under the old test.
My hope with this post is to have clarified the results of the new test for those trying to interpret their results. If you have any questions at all about the new test, and are having a hard time getting in touch with UC Davis, please don't hesitate to reach out to me: HeavenlyHarvestLLC@gmail.com.