Unexpectedly, we found that the distribution of the MTHFR C677T genotype was significantly different between APS patients with and without thrombocytopenia (p = 0.040), although the frequency of the C/T allele was 0.37/0.63 in APS patients with thrombocytopenia; this was not significantly different from its frequency (0.64/0.36) in patients without thrombocytopenia (p = 0.088). Here, MTHFR is linked to Thrombocytopenia.