MTHFR is an enzyme in the methylation cycle that converts 5,10MTHF to 5-MTHF Methylene-tetrahydrofolate reductase, basically the conversion of inactive vitamin B9 to active vitamin B9.  The MTHFR enzyme is vital for many biochemical processes in the body and is a major player in the methylation cycle.  A genetic problem interferes with your body’s ability to break down folates and folic acid into methylfolate, leading to a decrease in methylfolate production, methyl B12 production, and SAMe (S-Adenosyl Methionine).  Deficiencies in active folate (methylfolate) can cause many chronic neurological and metabolic health condition. Those with a mutation may experience heart disease, inflammation, difficult pregnancies, birth defects, and have trouble detoxifying (as mentioned above). Oftentimes, these mutations cause difficulty with processing folic acid into methyl-folate, which is critical to methylation. Methylation optimizes some important processes in your body including metabolism of hormones and production of DNA. Depending on the mutation variations, you could have trouble converting nutrients into vitamins, minerals, and proteins, and maintaining appropriate hormone and neurotransmitter levels. It can even affect cholesterol levels, brain function, and digestion.