目的鉴定Ⅰ型Stickler综合征一家系的致病突变。
方法采用家系调查研究方法，收集2012年6月在汕头国际眼科中心就诊的来自中国潮汕地区的Ⅰ型Stickler综合征一家系。对参与调查的家系成员进行病史采集及临床检查，包括视力、眼压、裂隙灯显微镜和眼底检查等，并由经验丰富的临床医生进行诊断。采集该家系5例患者和4名表型正常者的外周静脉血各5 ml并提取基因组DNA；采用全外显子测序技术及相关生物信息学筛查方法对先证者父亲Ⅲ-5进行全外显子测序及致病突变筛选；采用Sanger测序对突变进行验证；采用SIFT、Polyphen2、MutationTaster分析变异位点致病性；采用氨基酸多序列比对及UniProt结构域预测分析变异位点氨基酸保守性及蛋白质三维结构。
结果该家系为常染色体显性遗传方式。共4代39人，其中患者15例，表型正常者24人。先证者Ⅳ-4右眼高度近视、视网膜脱离、斜视，左眼盲；患者Ⅲ-5右眼高度近视、白内障，左眼眼球萎缩；患者Ⅳ-9双眼高度近视。患者Ⅲ-5全外显子测序结果显示， COL2A1基因26号外显子c.1693C>T：p.565Arg>Cys位点变异。Sanger测序分析结果显示， COL2A1突变仅存在于被检患者中，未出现在表型正常者中，符合家系共分离。该变异位点经SIFT、Polyphen2、MutationTaster预测分析为有害性突变，COL2A1蛋白氨基酸序列第565位精氨酸在人、小鼠、大鼠、牛、非洲爪蟾中高度保守，此氨基酸位于该基因的三螺旋功能结构域，此突变使蛋白质在三螺旋重复区域Gly-X-Y发生了变化，X位置的精氨酸残基变为半胱氨酸残基，影响纤维蛋白功能，从而产生致病性。
结论 COL2A1基因c.1693C>T变异为该家系的致病基因变异位点，该变异位点首次在国内报道。
ObjectiveTo identify the disease-causing mutation in a Chinese family with Stickler syndrome type 1.
MethodsThe pedigree investigation was conducted.A Chinese family with Stickler syndrome type 1 was enrolled in the Shantou International Eye Center in June 2012.Medical history collection and clinical examinations, such as vision, intraocular pressure, slit lamp microscopy and fundus, were carried out in all the included family members and the diagnosis was made by clinical experts.Total genomic DNAs were extracted from the peripheral blood samples (5 ml) obtained from 5 patients and 4 healthy members.The potential variant of the proband's father Ⅲ-5 were screened by whole exome sequencing (WES) and stepwise bioinformatic analysis.The segregation and mutation conformation of the variant was verified by Sanger sequencing.The pathogenicity of the variant was predicted by SIFT, Polyphen2, and MutationTaster.Conservation and three-dimensional structure of amino acid mutation were analyzed by multiple sequence alignment and UniProt.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Joint Shantou International Eye Center (No.EC20110310[2]-P02).Written informed consent was obtained from each subject or the guardian.
ResultsAn autosomal dominant inherence in 39 members of 4 generations including 15 patients and 24 phenotypically normal members was found in the family.The proband (Ⅳ-4) showed high myopia, retinal detachment and strabismus in the right eye, and the left eye was blind.A patient (Ⅲ-5) showed high myopia and cataract in the right eye, atrophy in the left eye.A patient (Ⅳ-9) showed binocular high myopia.A heterozygous variation, c.1693C>T: p.Arg565Cys, within the exon 26 of COL2A1 gene was revealed in patient Ⅲ-5, which was only found in the patients and not in phenotypically normal members, indiacating co-separation in this family.The variant was predicted to be a severe damage by SIFT, Polyphen2 and MutationTaster.The amino acid mutation at position 565 was highly conservative among human, mouse, rat, bovine and Xenopus laevis, which caused the arginine to cysteine substitution at the X position in triple helix repeat region Gly-X-Y, affecting the function of fibrous protein and becoming pathogenic.
ConclusionsVariant c.1693C>T: p.Arg565Cys in COL2A1 gene is disease-causing in this family and this is the first report about the variant in China.
邓芳,曹迎杰,谢丽静,等. 全外显子组测序法鉴定中国Ⅰ型Stickler综合征一家系致病基因[J]. 中华实验眼科杂志,2022,40(10)：935-939.
DOI:10.3760/cma.j.cn115989-20200612-00425版权归中华医学会所有。
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邓芳：设计试验、实施研究、采集数据、文章撰写和修改；曹迎杰、陈少婉：数据分析；谢丽静：收集病例、实施研究、解释数据；肖小强：设计试验、指导试验、文章智力性内容的修改及定稿；张铭志：设计试验、指导试验
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