Variation and expression of dihydrofolate reductase (DHFR) in relation to spina bifida.

The dihydrofolate reductase (DHFR) enzyme is important for folate availability, folate turnover and DNA synthesis. The 19-bp deletion in intron-1 of DHFR has been associated with the risk of having spina bifida affected offspring, supposedly by changing DHFR gene expression. A 9-bp repeat in exon 1 of the mutS homolog 3 (MSH3) gene was recently demonstrated to be also located in the 5'UTR of DHFR and may possibly affect DHFR gene expression as well.