The frequencies of 7 polymorphisms known to be implicated in thrombosis were: prothrombin FII G20210A (6.4%), FVR2 (16.4%), FVL (17.0%), FXIII V34L (41.5%), MTHFR C677T (57.9%), MTHFR A1298C (62.6%), and PAI-1 4G allele (78.9%) (Fig 1B). The gene discussed is MTHFR; the disease is deep vein thrombosis.