**6. Who should be tested for MTHFR mutations and homocysteine levels**

For individuals with unexplained arterial or venous blood clots and unexplained atherosclerosis it seems appropiate having blood homocysteine levels checked. One can also argue that everybody with atherosclerosis, patients with CVD, heart attacks, or strokes, should have their blood checked for homocysteine levels. All this in order to prevent further damage. At this time, no clear medical indication exists for women with a history of recurrent pregnancy loss, preeclampsia, placental abruption, and/or small-for-age babies to have homocysteine levels checked, although appropiate clinical research should come with more evidence for this.

As with homocysteine, no official guidelines exist as to who should be tested for MTHFR. In the absence of elevated homocysteine levels, MTHFR mutations appear to have no clinical relevance in regard to thrombosis and atherosclerosis. However, in case of elevated homocysteine levels of MTHFR patients the risk for venous thromoembolism increases dramatically. Since treatment can be relatively easy according to diet, one could argue that there is indication to perform MTHFR genetic testing after the homocysteine test shows elevated levels (Varga et al., 2005).
