NAD Deficiency, Congenital Malformations, and Niacin Supplementation
NAD Deficiency, Congenital Malformations, and Niacin Supplementation
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DOI：
10.1056/nejmoa1616361
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发表时间：
2017-08-10
影响因子：
158.5
通讯作者：
Dunwoodie, Sally L.
中科院分区：
文献类型：
--
作者：
Shi, Hongjun;Enriquez, Annabelle;Dunwoodie, Sally L.
先天性畸形可以表现为表型的组合，其共同发生的频率比预期的更高。在许多这样的情况下，已经证明很难确定遗传原因。我们寻求心脏，脊椎，肾缺陷的遗传原因，除其他外，在无关patients.METHODSWe使用基因组测序，以确定潜在的致病基因变异的家庭中，一个人有多个先天性畸形。我们通过使用体外酶活性测定和通过定量患者血浆中的代谢物来测试变体的功能。我们使用CRISPR（成簇规则间隔短回文重复序列）-Cas9系统工程化具有类似变体的小鼠模型。在编码犬尿氨酸途径的酶3-羟基邻氨基苯甲酸3，4-双加氧酶（HAAO）和犬尿氨酸酶（KYNU）的两个基因中鉴定了突变体。3名患者携带预测HAAO或KYNU蛋白功能丧失变化的纯合变体（HAAO p.D162 *、HAAO p.W186 * 或KYNU p.V57Efs * 21）。另一名患者携带杂合KYNU变体（p.Y156 * 和p.F349Kfs * 4）。突变酶在体外的活性大大降低。烟酰胺腺嘌呤二核苷酸（NAD）通过犬尿氨酸途径从色氨酸从头合成。患者的循环NAD水平降低。由于NAD缺乏，Haao-null或Kynu-null小鼠的胚胎中出现了与患者相似的缺陷。在null小鼠，在妊娠期预防NAD缺乏避免defects. CONCLUSIONSDrupture的NAD合成造成的缺乏NAD和先天性畸形在人类和小鼠。妊娠期补充烟酸可预防小鼠畸形。（由澳大利亚国家健康和医学研究理事会和其他机构资助。
BACKGROUNDCongenital malformations can be manifested as combinations of phenotypes that co-occur more often than expected by chance. In many such cases, it has proved difficult to identify a genetic cause. We sought the genetic cause of cardiac, vertebral, and renal defects, among others, in unrelated patients.METHODSWe used genomic sequencing to identify potentially pathogenic gene variants in families in which a person had multiple congenital malformations. We tested the function of the variant by using assays of in vitro enzyme activity and by quantifying metabolites in patient plasma. We engineered mouse models with similar variants using the CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 system.RESULTSVariants were identified in two genes that encode enzymes of the kynurenine pathway, 3-hydroxyanthranilic acid 3,4-dioxygenase (HAAO) and kynureninase (KYNU). Three patients carried homozygous variants predicting loss-of-function changes in the HAAO or KYNU proteins (HAAO p.D162*, HAAO p.W186*, or KYNU p.V57Efs*21). Another patient carried heterozygous KYNU variants (p.Y156* and p.F349Kfs*4). The mutant enzymes had greatly reduced activity in vitro. Nicotinamide adenine dinucleotide (NAD) is synthesized de novo from tryptophan through the kynurenine pathway. The patients had reduced levels of circulating NAD. Defects similar to those in the patients developed in the embryos of Haao-null or Kynu-null mice owing to NAD deficiency. In null mice, the prevention of NAD deficiency during gestation averted defects.CONCLUSIONSDisruption of NAD synthesis caused a deficiency of NAD and congenital malformations in humans and mice. Niacin supplementation during gestation prevented the malformations in mice. (Funded by the National Health and Medical Research Council of Australia and others.)