摘要
目的确定1个具有无色素性视网膜色素变性(RPSP)表型的Usher综合征(USH)家系的致病基因及其与眼部表现相关性。方法回顾性临床研究。2019年11月于河南省人民医院眼科门诊检查确诊的具有RPSP表现的1F型USH患儿1例和其父母纳入研究。患儿女,9岁。双眼夜盲4年余;听力下降7年,目前双耳感音神经性耳聋。双眼最佳矫正视力0.5+。眼底未见明显色素沉着。外围视野视敏度下降。光相干断层扫描检查,周边视网膜外层变薄,椭圆体带消失。视网膜电图检查,视杆、视锥系统反应重度下降。患儿父母临床表型正常。抽取患儿及其父母外周静脉血,提取全基因组DNA,采用自主研发的靶向捕获试剂盒(PS400),使用二代基因测序技术检测基因变异,对可疑致病突变位点通过Sanger测序进行验证,并在家系成员中进行共分离。依据序列变异解读标准和指南对变异进行致病性评估;利用生物信息学技术评估变异对编码蛋白的影响。结果基因检测结果显示,先证者检测到PCDH15基因c.4109dupA(p.K1370fs)(M1)、c.17dupA(p.Y6_L7delinsX)(M2)复合杂合突变位点,经Sanger测序验证,变异在该家系中呈共分离状态。经序列变异解读标准和指南评估,M1、M2均为PCDH15基因致病性变异,M1导致编码蛋白跨膜结构完全改变,M2导致基因仅能翻译出6个氨基酸,预测不能合成PCDH15蛋白。根据临床表型、基因变异致病性以及蛋白结构预测,最终临床诊断为PCDH15相关1F型USH。结论PCDH15基因c.4109dupA、c.17dupA为该家系患儿USH的致病突变位点,该复合杂合新突变导致PCDH15蛋白无法正常合成,从而引起眼部及耳部表现。
Objective To identify the causative gene in a family affected with Usher syndrome(USH)with retinitis pigmentosa sine pigmento(RPSP)and to analyze the genotype-phenotype correlation.Methods A retrospective clinical study.A 9-year-old girl with RPSP type 1F USH diagnosed in the ophthalmology clinic of Henan Provincial People's Hospital in November 2019 and her parents were included in the study.The patient had bilateral night blindness for more than 4 years,she suffered from hearing loss 7 years,and is currently binaural sensorineural deafness.The best corrected visual acuity in both eyes was 0.5+.There was showed no obvious pigmentation on the fundus.The visual acuity of the peripheral field of vision decreased.Optical coherence tomography showed that the outer layer of the peripheral retina became thinner and the ellipsoid band disappeared.On electroretinogram examination,the rod and cone system response was severely decreased.The clinical phenotype of the parents of the child were normal.The peripheral venous blood of the child and his parents were extracted,the whole genome DNA was extracted,the custom developed targeted capture kit(PS400)was used,and the next-generation sequencing technology was used to detect genetic mutations.The suspected pathogenic mutation sites were verified by Sanger;co-segregation was performed among family members.The pathogenicity of variants were evaluated according to the interpretation standards and guidelines of sequence variants.Bioinformatics techniques were used to assess the impact of variants on encoded proteins.Results The results of genetic testing showed that the proband detected the PCDH15 gene c.4109dupA(p.K1370fs)(M1),c.17dupA(p.Y6_L7delinsX)(M2)compound heterozygous mutation sites,verified by Sanger sequencing,the mutations were in the family in a state of co-segregation.According to the evaluation of sequence variation interpretation standards and guidelines,M1 and M2 were pathogenic variants of the PCDH15 gene.M1 led to a complete change in the transmembrane structure of the encoded protein,and M2 caused the gene to only translate 6 amino acids,which predicted that the PCDH15 protein cannot be synthesized.According to the clinical phenotype,gene mutation pathogenicity and protein structure prediction,the final clinical diagnosis was PCDH15-related type 1F.Conclusions PCDH15 genes c.4109dupA and c.17dupA are the pathogenic mutation sites of USH in this family.These compound heterozygous new mutations lead to the failure of normal synthesis of PCDH15 protein,which leads to ocular and ear manifestations.
作者
朱青
李亚
游雅
施晓萌
雷博
Zhu Qing;Li Ya;You Ya;Shi Xiaomeng;Lei Bo(Zhengzhou University People’s Hospital,Henan Provincial People’s Hospital,Henan Eye Institute&Henan Eye Hospital,Henan Provincial Eye Hospital,Henan Clinical Research Center for Ophthalmic Diseases,Zhengzhou 450003,China)
出处
《中华眼底病杂志》
CAS
CSCD
北大核心
2021年第6期444-448,共5页
Chinese Journal of Ocular Fundus Diseases
基金
国家自然科学基金(81770949)。
