DHFR（dihydrofolate reductase），癌症关联基因，基因ID：1719，二氢叶酸还原酶将二氢叶酸转化为四氢叶酸，这是嘌呤、胸苷酸和某些氨基酸从头合成所需的甲基穿梭剂。功能性二氢叶酸还原酶基因已被定位到5号染色体上，多个无内含子处理的假基因或类似二氢叶酸还原酶的基因已被鉴定在不同的染色体上。二氢叶酸还原酶缺乏与巨幼细胞性贫血有关。已经发现了一些编码不同亚型的转录变体。[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]。