Analysis of the MTHFR A1298C frequency data obtained in this study showed that the heterozygotes (AC) were overrepresented in MS patients (67.8% versus 45.7%, P= 0.00) and a small trend for a higher frequency of the homozygous mutant genotype (CC) was observed in controls (11.8% versus 2.8%, P= 0.04). Here, MTHFR is linked to myeloid sarcoma.