RESUMEN
OBJECTIVE: Folic acid insufficiency is a known risk factor for neural tube defects (NTDs), while the role of vitamin B12 is questionable. Thus, our purpose was to investigate whether low maternal serum vitamin B12 is associated with an increased risk of NTDs. SETTING: Prenatal Diagnosis and Clinical Genetics Clinics, National Research Centre, in collaboration with the Radioisotope Department, Nuclear Research Centre, Cairo. MATERIALS AND METHODS: The study groups included 36 women who were, or had been, pregnant with a NTD-affected fetus. The control groups comprised 35 healthy women with normal prior or current pregnancy and uncomplicated obstetric histories. Fasting plasma homocysteine, serum folate and cobalamin (vitamin B12) were determined. Odds ratio (OR) and 95% confidence intervals were calculated. RESULTS: The fasting homocysteine was significantly higher in the study groups as compared to the controls. The median serum folate concentrations were similar in cases and controls, while the median vitamin B12 concentrations were significantly lower in the study groups compared to the controls. Low vitamin B12 concentration was associated with an approximately 2- to 3-fold increased risk for NTDs. CONCLUSION: Low maternal serum values of vitamin B12 can be considered an important etiologic factor for the development of neural tube defects in our population. This may help in both genetic counseling for families with a history of NTD malformation, and as a pre-conceptional prophylactic measure by maternal supplementation of vitamin B12 and folic acid.