MTHFR and hyperhomocysteinemia: For example, in the Netherlands, 14% to 16% of mothers and 10% to 15% of fathers of children with spina bifida, and 3% to 18% of those children had a homozygous mutation in the MTHFR gene, while the incidence of this mutation in the normal population was only 5%.[11–13] Acquired hyperhomocysteinemia is caused by insufficient intake of dietary folate, Vitamin B6 or Vitamin B12, and/or the use of certain medications.