I've been doing a fair amount of research around the COMT V158M +/+ (also known as AA or Met/Met) result, and it seems that the COMT SNP is a pretty cast-iron diagnosis, not an indication of inclination..
The many scientific studies out there that cover the COMT V158M (also known as rs4680 or Val158Met) polymorphism include it because it affects the treatment for Parkinson's and Schizophrenia (it's all about money when it comes to studies being done or not).
If you give Parkinson's and Schizophrenia drugs to people with the polymorphism, they will react badly to it. That's because the drugs LOWER COMT activity, which for people whose COMT activity is already too low, will mean their dopamine, epinephrine, and norepinephrine levels will go through the roof.
"It is an extremely well-studied polymorphism with 165 papers referencing it on pubmed as of 2012."
"In this case that single amino acid change from valine to methionine [the polymorphism] has a dramatic impact on the protein’s function."
"The Val158Met polymorphism in the COMT gene leads to an amino-acid substitution (valine (Val) to methionine (Met)) and results in the Met/Met variant showing 40% less enzymatic activity than the Val/Val."
from
http://www.nature.com/npp/journal/v33/n13/full/npp200882a.html
Other links:
https://neuroamer.wordpress.com/201...-one-gene-comt-catechol-o-methyl-transferase/
And
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1182110/pdf/AJHGv75p807.pdf
Am I right here? Or barking up the wrong tree?