Treatment with 5-MTHF to support the one-carbon cycle can overcome the deleterious impact of a triple SNP mutation in the male partner's MTHFR gene for a couple with a history of repeated miscarriage.

A couple presenting with more than 3 years' history of infertility and three miscarriages was tested for serum homocysteine levels and for the two principal MTHFR SNPs: 677C < T and 1298A < C, as per our general policy for patients with infertility of long duration. The woman was found to be wild type for both MTHFR SNPs with a serum homocysteine 10.5 µM, slightly higher than our accepted normal value of 8.5 µM. The man was found to be a carrier of a triple mutation for 677C < T and 1298 A < C, with an elevated homocysteine level of 19 µM. Since high doses of folic acid (FA) exacerbate perturbations in the DNA methylome, the husband was treated with 5-methyl tetrahydrofolate together with nutritional support of the one-carbon cycle (OCC). After 3 months of treatment, the couple conceived, and the woman delivered a healthy female baby. Three years later, she again conceived and delivered a second healthy female baby. Our treatment can restore fertility in males affected by a triple SNP mutation in the MTHFR gene; this confirms that Hcy and MTHFR SNP testing should not be overlooked in patients affected by long duration of infertility/repeat miscarriages.