We did the Neurogenomic Profile, which I believe was a cheek swab, if I remember correctly. It was a kit and was mailed in. Many people do 23 and Me for this information, because you also get a ton more information with that test.
What’s most important is finding someone who is really knowledgable about MTHFR, which is very difficult. The integrative meds doc that suggested the test for my son and gave us the kit, really didn’t have a good understanding of what to do to address it. We actually had worse outcomes with the treatment she suggested and ending up not supplementing for it at all for two years, not knowing what to do and not getting positive results. I came back to it about a year ago, supplementing with 1-2 items at a time and very low doses, and had more success.
Addressing the MTHFR didn’t change any ADHD symptoms for my son, but it did help with medication sensitivities and that sort of thing.
ADDitude Community Moderator, Author & Mentor on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism