Hello, I am new to this forum, but I have been reading a great deal of the posts about methylation and b12 and other treatments. In my case, I have been researching a great deal about methylation after reading Dr. William Walsh's book Nutrient Power because I suffer from OCD, which introduced me to the topic of methylation and its implications in psychiatric disorders/ physical ailments. After reading his book I did the first thing he recommended to determine my methylation status and I had a whole blood histamine test, which resulted in 103ng/ml (not 100% sure on the unit of measure). Anyways according to Walsh, "normal" histamine is between 40-70 ng/ml and anything above and below indicated over and undermethylator as I am sure some of you are aware. My high histamine puts me in the "undermethylation" status, which is what I expected as I fit much more of the high histamine profile than I do the low histamine profile. After all of the reading I have done on this subject I have a few questions for those of you who are experienced with this topic. 1) aside from either Yasko's or 23andMe's SNP tests (I am waiting on 23andMe for my results currently), what other blood tests would be useful in determining my current condition? Does anyone know of a good provider of these tests? Are these tests possible through my primary physician and possible to be covered by insurance? Personally I think knowing my homocysteine status would be a good thing, and possibly my b12 status. 2) Can undermethylated types have either high OR low homocysteine? From what I know, some people have CBS upregulations and therefore don't have the homocysteine necesarry to produce enough methionine. Meanwhile some other people have issues with MTHFR, MTRR, and MTR which prohibit enough homocysteine to be converted back into methionine due to bottlenecking or sheer inability to catalyze the conversion. Are these both potential causes of undermethylation? Are there others? 3) For anyone who has read Dr. Walsh's book, why does he say that b12 is bad for undermethylators (he says b12 and folate are both bad as they can cause methyl trapping). But I have read other sources that indicate methyl trapping is the result of lacking b12 and an overabundance of 5mthf that cannot donate its methyl group to a finally convert homocysteine. In Walsh's book he also says that folate (and b12 I think) cause acetylation, which is essentailly the opposite effect that methylation has on DNA, but I googled the subject and could not really find much material regarding folate and acetylation anywhere, so I am not sure about this. Any help on these questions would be much appreciated.