A specific form of the MTHFR gene associated with depression risk is pro-inflammatory and offers protection against Hepatitis B.

“So if you make a list, think about something like MTHFR gene that’s involved in folate metabolism right? So there’s a form of it that seems to be a depression risk factor. So if you look at what it does immunologically, it is probably pro-inflammatory. And it’s strongly associated with increased survival in sub-Saharan Africa, because in sub-Saharan Africa, so many people innocently die of Hepatitis B, and the form of the gene that may be a risk factor for depression is actually protective against that illness.”