NICHD HEALTH RESEARCH BOARD OF IRELAND NEURAL TUBE DEFECTS STUDY

流行病学分支（DESPR）正在进行一些研究， 与健康研究委员会和Trinity学院合作， 爱尔兰。 这些调查旨在确定生物化学 叶酸降低神经管缺陷风险的机制。 数据和血液样本已经收集了很大一部分爱尔兰人， 在都柏林分娩的妇女。 妊娠妇女的样本 结果是一个神经管缺陷的孩子出生了， 那些以正常分娩而终止妊娠的妇女， 研究了 样本也正在从受影响的家庭收集。 孩子 叶酸代谢的各个方面和其他营养 正在研究措施。 我们已经证明，在较低的水平上， 在B12中，携带NTD胎儿的妇女 同型半胱氨酸水平高于怀有正常胎儿的妇女。 我们还 研究表明，一种负责消除 同型半胱氨酸也有关系 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明显更多 在NTD患者中的发生率高于正常人。 我们最近发表的一份报告显示， MTHFR的不耐热变体与显著降低的 红细胞叶酸水平 一篇即将出版的论文表明， 引起大多数同型胱氨酸尿症的是胱硫醚合酶， 尽管它与神经管缺陷有关，但不是神经管缺陷的重要原因。 高同型半胱氨酸

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.