Although several studies have suggested that patients with homozygous MTHFR C677T were more likely to be subject to an increased number of thrombosis events, and that they had a lower mean age at the first thrombosis event than patients with non-homozygous MTHFR C677T, previous studies showed no significant difference between the MTHFR C677T genetic distribution in APS patients and the healthy group [13,17,18]. The gene discussed is MTHFR; the disease is deep vein thrombosis.