CT genotype increases the risk of neural tube defect

Being heterozygous for the T allele of the MTHFR gene (for the folate dependent enzyme 5,10 methylenetetrahydrofolate reductase) raises the risk of neural tube defect. Analysing the DNA sequences of 395 people with neural tube defect and 848 controls in Ireland, Kirke and colleagues (p 1535) confirmed that the risk is increased for carriers of the homozygous TT genotype, and also for the CT genotype. Heterozygosity may be a risk factor for conditions common in homozygosity, such as ischaemic heart disease, say the authors.