NICHD HEALTH RESEARCH BOARD OF IRELAND NEURAL TUBE DEFECTS STUDY

流行病学处(DESPR)正在进行一系列研究。 与健康研究委员会和三一学院合作， 爱尔兰。这些调查的目的是为了确定 叶酸降低神经管缺陷风险的机制。 收集了很大一部分爱尔兰人的数据和血样 在都柏林接生的妇女。从怀孕妇女身上采集的样本 以分娩神经管缺陷的孩子而告终 以正常分娩而终止妊娠的妇女正在接受 学习。还在从受影响的家庭中收集样本。 孩子。叶酸代谢的各个方面和其他营养 目前正在研究各项措施。我们已经在较低的水平上证明了这一点 在B12中，怀有NTD胎儿的女性明显更高 同型半胱氨酸水平高于怀有正常胎儿的妇女。我们还有 证明了一种异常基因负责消除 同型半胱氨酸也参与其中。具体地说，基因缺陷会产生 所谓的5，10-亚甲基四氢叶酸的不耐热变体 还原酶。这种异常的酶被发现的明显更多 常见于NTDS患者，而不是正常人。 我们最近发表的一份报告显示， 亚甲基四氢叶酸还原酶不耐热变异与显著降低有关 红血球叶酸水平。一篇正在出版的论文表明，这种酶 导致大多数同型半胱氨酸尿症的是胱硫氨酸合成酶 不是神经管缺陷的重要原因，尽管它与 同型半胱氨酸含量高。

The Epidemiology Branch (DESPR) is conducting a number of studies in collaboration with the Health Research Board and Trinity College, Ireland. These investigations are designed to determine the biochemical mechanisms by which folate reduces the risk for neural tube defects. Data and blood samples have been collected on a large proportion of Irish women delivering babies in Dublin. Samples from women whose pregnancy ended in the delivery of a child with a neural tube defect and control women whose pregnancy ended in the delivery of a normal child are being studied. Samples are also being collected from families with an affected child. Various aspects of folate metabolism and other nutritional measures are being examined. We have demonstrated that at lower levels of B12, women carrying a fetus with an NTD have significantly higher levels of homocysteine than women carrying a normal fetus. We have also demonstrated that an abnormal gene responsible for elimination of homocysteine is involved. Specifically, a gene defect produces the so-called thermolabile variant of the 5,10 methylene tetrahydrofolate reductase enzyme. This abnormal enzyme is found significantly more frequently in individuals with NTDs than in normal individuals. We have recently published a report showing that the presence of the thermolabile variant of MTHFR is associated with significantly reduced levels of red cell folate. A paper in press shows that the enzyme responsible for most cases of homocystinuria, cystathionine synthase, is not an important cause of neural tube defects despite its association with high homocysteine.