Abstract: Folate is an essential water-soluble vitamin for the human body，involved in various metabolic processes. Defects in enzymes related to folate metabolic passway and transport carriers of folate can lead to diseases. Patients with folate metabolic disorders primarily exhibit neurological and psychiatric symptoms as well as abnormalities in the hematopoietic system. The keys to diagnosis include the detection of 5-methyltetrahydrofolate in serum and cerebrospinal fluid and genetic sequencing. With early diagnosis，most patients can achieve good outcome through folate supplementation.

Key words: folate, 5-methyltetrahydrofolate, folate transport, megaloblastic anemia

摘要： 叶酸是人体必需的水溶性维生素，参与多种代谢过程，叶酸代谢通路相关酶以及叶酸转运载体缺陷都可导致疾病。叶酸代谢障碍疾病患儿以神经精神症状、血液系统异常为主要表现，血清、脑脊液5- 甲基四氢叶酸检测及基因测序是诊断的关键，如果能够早期诊断，通过叶酸制剂补充治疗，大多数患儿病情可获得良好的转归。

关键词: 叶酸, 5-甲基四氢叶酸, 叶酸转运, 巨幼细胞性贫血