It sounds like progress is being made with MTHFR in some areas...

Testing DNA to find best meds to fight depression

http://www.chicagotribune.com/lifest...827-story.html

"Most significantly, testing showed Mandy had a single mutation in the MTHFR enzyme critical in metabolizing folate found in foods or vitamin supplements. Researchers showed in the 1960s that folate deficiency could trigger depression. Genetic testing can reveal enzyme mutations linked to commonly consumed drugs and vitamins.

Rosenbloom gave Mandy a prescription form of processed folate, l-methylfolate, that can cross the blood-brain barrier and switch on enzymes that would help her metabolize antidepression medicines such as Wellbutrin."