Chen Hongbo, Qian Yanyan, Yu Sha, Xiao Deyong, Guo Xiao, Wang Qing, Hao Lili, Yan Kai, Lu Yulan, Dong Xinran, Zhou Wenhao, Wu Bingbing, Zhou Shuizhen, Wang Huijun
Shanghai Key Lab of Birth Defects, Pediatrics Research Institute, Children's Hospital of Fudan University Shanghai, 201102, China.
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China.
Eur J Med Genet. 2019 Feb;62(2):149-160. doi: 10.1016/j.ejmg.2018.07.002. Epub 2018 Jul 6.
Developmental delay (DD) is a neurological disorder that presents with defects in gross motor, fine motor, language and cognition functions. WD repeat domain 45 (WDR45) is one of the disease-causing genes of DD. Previously, WDR45 de novo mutations were reported in certain adult and pediatric patients due to iron accumulation.
We report five pediatric female patients with DD and epilepsy. Their ages were below 3 years at the first consultation, and precise diagnoses were difficult based on the available clinical information and phenotype.
Children with DD and/or epilepsy presenting to the molecular diagnostic center of Children's Hospital of Fudan University between May 2016 and May 2017 were enrolled. The patients and their parents were subjected to whole-exome sequencing (WES), and we characterized the phenotypes of the patients carrying WDR45 variants. Furthermore, we overexpressed the candidate variants in HeLa cells and evaluated their effect on autophagy through Western blot and immunofluorescence staining with confocal microscopy.
Five WDR45 de novo mutations, namely, c.19C > T (p.Arg7*), c.401G > C (p.Arg134Pro), c.503G > A (p.Gly168Glu), c.700C > T (p.Arg234*), and c.912delT (p.Ala305Leufs*25), were detected in 623 enrolled pediatric patients (274 females; 487 patients younger than 6 years). All five patients with WDR45 variants presented with DD and epilepsy. Compared with the control HeLa cells, the cells with the p. Arg134Pro and p. Gly168Glu missense mutations showed accumulation of LC3-containing autophagic structures and an abnormally enlarged cell volume, and Western blotting revealed a significant increase in LC3II/GAPDH.
The identification of WDR45 mutations provides further evidence that WES plays an important role in the diagnosis of neurological disorders with common phenotypes and that WDR45 mutations are associated with neurological disorders and are not very rare in Chinese female pediatric patients with DD and/or epilepsy. The diagnosis of patients with WDR45 mutations would enable more precise genetic counseling for the parents of these children.
发育迟缓（DD）是一种神经障碍，表现为大运动、精细运动、语言和认知功能缺陷。WD重复结构域45（WDR45）是DD的致病基因之一。此前，由于铁蓄积，在某些成年和儿科患者中报道了WDR45新发突变。
我们报告了5例患有DD和癫痫的儿科女性患者。她们在首次就诊时年龄均小于3岁，基于现有的临床信息和表型难以做出准确诊断。
纳入2016年5月至2017年5月在复旦大学附属儿科医院分子诊断中心就诊的患有DD和/或癫痫的儿童。对患者及其父母进行全外显子组测序（WES），我们对携带WDR45变异的患者的表型进行了特征分析。此外，我们在HeLa细胞中过表达候选变异，并通过蛋白质免疫印迹法以及共聚焦显微镜免疫荧光染色评估它们对自噬的影响。
在623名纳入研究的儿科患者（274名女性；487名年龄小于6岁的患者）中检测到5种WDR45新发突变，即c.19C>T（p.Arg7*）、c.401G>C（p.Arg134Pro）、c.503G>A（p.Gly168Glu）、c.700C>T（p.Arg234*）和c.912delT（p.Ala305Leufs*25）。所有5例携带WDR45变异的患者均表现为DD和癫痫。与对照HeLa细胞相比，携带p.Arg134Pro和p.Gly168Glu错义突变的细胞显示含LC3的自噬结构蓄积且细胞体积异常增大，蛋白质免疫印迹法显示LC3II/GAPDH显著增加。
WDR45突变的鉴定进一步证明WES在具有常见表型的神经障碍诊断中发挥重要作用，并且WDR45突变与神经障碍相关，在中国患有DD和/或癫痫的儿科女性患者中并非非常罕见。对携带WDR45突变的患者进行诊断将能够为这些患儿的父母提供更精准的遗传咨询。
