It may be possible that vitamin B12 deficiency either results in a virtual deficiency of folic acid thereby affecting methyl group supply or PEMT may be epigenetically altered leading to reduced expression affecting the conversion of PE-DHA (phosphatidyl ethanolamine-DHA) to PC-DHA (phosphatidyl choline-DHA) resulting in lower DHA levels in placenta. The gene discussed is PEMT; the disease is vitamin B12 deficiency.