this site (thanks Donna P ) has some good explanations of the genetic variables and what it means for your methylation cycle.
We discuss Vit D supplementation alot and I found this part interesting. What your Vit D receptor Genes status is (and your gene status of other key genes linked to methylation) - may explain how you respond to Vit D supplementation - as it is linked with the methylation cycle...
Like most things in MC world, there is no black and white or easy summary to all of this, each individuals variables of multiple gene mutations affect things. Albeit it does explain why someone will have fantastic response to a diet change or supplement change within weeks, and why another person it may take months to see benefit or they dont feel it is helping them at all.
http://www.heartfixer.com/AMRI-Nutrigenomics.htm#MTR: Methionine Synthase
Individuals with a normal Vitamin D receptor, those who are VDR Taq (-/-), make plenty of dopamine. They tend not to need or to tolerate methyl groups or dopamine precursor substances. With respect to methyl group need and tolerance, they behave like COMT (+) individuals. Individuals (+/+) or (+/-) for VDR Taq defect have lower Vitamin D levels, make less dopamine, and will need and tolerate dopamine precursor substances and methyl donors. With respect to methyl donor tolerance, VDR Taq (+) individuals behave like COMT (-) individuals. All sorts of permutations are possible here, impacting on your tolerance and need for dopamine precursors and methyl groups. I acknowledge that this is all very difficult to understand.
Tex: another interesting thing on this web page is the info about MTR & MTRR gene mutations.
if you have MTR A2756G mutation then your B12 blood levels may be normal, but your methyl B12 will be low.
then as you get into the MTRR, my interpretation of what the site says, based on my gene mutation results, is that i need both forms of B12.
I feel like Alice in Wonderland, what at first was really weird and strange, captivates me and is a magical world - where on the surface nothing makes sense, but then it makes more sense and I wonder why I didnt find this magical place earlier!!