Hepatitis B surface antigenaemia in a child after vaccination

1. Davis RE. Folate supplementation [letter]. Med J Aust 1992; 157: 425. 2. van der Put NMJ, Steegers-Theunissen RPM, Frosst P, et al. Mutated methylenetetrahydrofolate reductase as a risk factor for spina bifida. Lancet1995; 346: 1070-1071. 3. MRCVitaminStudy ResearchGroup. Preventionof neural-tube defects: results of the Medical ResearchCouncil vitamin study. Lancet1991; 338: 131-137. 0 It is possible to measure the urinary excretion of homocysteine, but at present this test probably lacks the required sensitivity. It should be remembered that women with this abnormal reductase tend to have a serum folate concentration at the lower end of the reference range. The abnormality can be determined at any time with this screening procedure and this will enable those at risk to take pharmacological doses of folate before conception.