Hmm. Good question. I think they'd have to test for the methylated versions, not the regular versions, and I do not know whether the standard procedure is to test for the methylated versions - but this is just me reasoning it out, not medical advice. To my knowledge, if MTHFR is suspected, they generally test for the MTHFR mutation itself.
P/S/A: There are single sentences which can create life-changing amounts of difference.