They are not the same thing but they are related. MTHFR is a genetic snp that is responsible for taking all the folate you eat and turning it into methylfolate. Methylfolate is important for the Methionine cycle. The Methionine (Methylation) cycle takes homocysteine, converts it into methionine (using several co-nutrients) which then makes SAM.
Pre-menstrual syndrome (PMS) is that time of the month just before a woman’s cycle starts where her hormones may feel completely out of balance resulting in mood swings (!), tender breasts, weight gain, acne, and fatigue. The hormones responsible are primarily a balance between progesterone and estrogen however other hormones such as cortisol (from the adrenals) and serotonin (the brain hormone) can play a role.