二氫葉酸還原酶將二氫葉酸轉化為四氫葉酸，這是嘌呤、胸苷酸和某些氨基酸從頭合成所需的甲基穿梭劑。功能性二氫葉酸還原酶基因已被定位到5號染色體上，多個無內含子處理的假基因或類似二氫葉酸還原酶的基因已被鑒定在不同的染色體上。二氫葉酸還原酶缺乏與巨幼細胞性貧血有關。已經發現了一些編碼不同亞型的轉錄變體。[由RefSeq提供，2014年3月]
Dihydrofolate reductase converts dihydrofolate into tetrahydrofolate, a methyl group shuttle required for the de novo synthesis of purines, thymidylic acid, and certain amino acids. While the functional dihydrofolate reductase gene has been mapped to chromosome 5, multiple intronless processed pseudogenes or dihydrofolate reductase-like genes have been identified on separate chromosomes. Dihydrofolate reductase deficiency has been linked to megaloblastic anemia. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Mar 2014]