Department of Clinical Genetics, Erasmus MC Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
Circ Res. 2012 Jun 8;110(12):1564-74. doi: 10.1161/CIRCRESAHA.112.269795. Epub 2012 May 1.
Congenital heart malformations are a major cause of morbidity and mortality, especially in young children. Failure to establish normal left-right (L-R) asymmetry often results in cardiovascular malformations and other laterality defects of visceral organs.
To identify genetic mutations causing cardiac laterality defects.
We performed a genome-wide linkage analysis in patients with cardiac laterality defects from a consanguineous family. The patients had combinations of defects that included dextrocardia, transposition of great arteries, double-outlet right ventricle, atrioventricular septal defects, and caval vein abnormalities. Sequencing of positional candidate genes identified mutations in NPHP4. We performed mutation analysis of NPHP4 in 146 unrelated patients with similar cardiac laterality defects. Forty-one percent of these patients also had laterality defects of the abdominal organs. We identified 8 additional missense variants that were absent or very rare in control subjects. To study the role of nphp4 in establishing L-R asymmetry, we used antisense morpholinos to knockdown nphp4 expression in zebrafish. Depletion of nphp4 disrupted L-R patterning as well as cardiac and gut laterality. Cardiac laterality defects were partially rescued by human NPHP4 mRNA, whereas mutant NPHP4 containing genetic variants found in patients failed to rescue. We show that nphp4 is involved in the formation of motile cilia in Kupffer's vesicle, which generate asymmetrical fluid flow necessary for normal L-R asymmetry.
NPHP4 mutations are associated with cardiac laterality defects and heterotaxy. In zebrafish, nphp4 is essential for the development and function of Kupffer's vesicle cilia and is required for global L-R patterning.
先天性心脏畸形是发病率和死亡率的主要原因，尤其是在幼儿中。未能建立正常的左右（L-R）不对称通常会导致心血管畸形和其他内脏器官的偏侧性缺陷。
确定导致心脏偏侧性缺陷的基因突变。
我们对一个来自近亲家庭的患有心脏偏侧性缺陷的患者进行了全基因组连锁分析。这些患者的缺陷组合包括右旋心、大动脉转位、双出口右心室、房室间隔缺损和腔静脉异常。对位置候选基因进行测序，发现 NPHP4 基因突变。我们对 146 例具有类似心脏偏侧性缺陷的无血缘关系的患者进行了 NPHP4 的突变分析。这些患者中有 41%还存在腹部器官的偏侧性缺陷。我们发现了 8 个额外的错义变异，这些变异在对照中不存在或非常罕见。为了研究 nphp4 在建立 L-R 不对称中的作用，我们使用反义形态发生素在斑马鱼中敲低 nphp4 的表达。nphp4 的耗竭破坏了 L-R 模式以及心脏和肠道的偏侧性。含有患者中发现的遗传变异的突变型 NPHP4 未能挽救，而人类 NPHP4 mRNA 部分挽救了心脏偏侧性缺陷。我们表明 nphp4 参与了 Kupffer 囊中的运动纤毛的形成，Kupffer 囊中的运动纤毛产生了正常 L-R 不对称所必需的不对称流体流动。
NPHP4 突变与心脏偏侧性缺陷和异构性有关。在斑马鱼中，nphp4 对于 Kupffer 囊纤毛的发育和功能至关重要，并且对于全局 L-R 模式至关重要。
