KMT2D基因新发双突变致歌舞伎面谱综合征的研究  

Two novel and de novo KMT2D mutations on the same allele cause Kabuki syndrome

作　　者：吴钊仪 岳海棠 李健[2] 杨解纲 边专[1] 何淼[1] Wu Zhaoyi;Yue Haitang;Li Jian;Yang Jiegang;Bian Zhuan;He Miao(State Key Laboratory of Oral&Maxillofacial Reconstruction and Regeneration,Key Laboratory of Oral Biomedicine Ministry of Education,Hubei Key Laboratory of Stomatology,School&Hospital of Stomatology,Wuhan University,Wuhan 430079,China;Department of Orthognathic&Cleft Lip and Palate Plastic Surgery,School&Hospital of Stomatology,Wuhan University,Wuhan 430079,China)

机构地区：[1]武汉大学口腔医(学)院、口颌系统重建与再生全国重点实验室、口腔生物医学教育部重点实验室、口腔医学湖北省重点实验室,武汉430079 [2]武汉大学口腔医(学)院正颌与唇腭裂整形外科,武汉430079

出　　处：《中华口腔医学杂志》2023年第8期809-814,共6页Chinese Journal of Stomatology

基　　金：国家自然科学基金(U22A20313,81970904,81970923,82170944)。

摘　　要：目的通过筛查1例歌舞伎面谱综合征(Kabuki syndrome,KS)患者的致病基因并分析其可能的致病机制,为KS的遗传咨询、产前筛查和产前诊断以及早期治疗提供依据。方法纳入2020年12月就诊于武汉大学口腔医(学)院正颌与唇腭裂整形外科的1例16岁女性KS患者,收集患者及其家系成员的临床资料、外周肘静脉血样本,通过改良盐析法提取基因组DNA,全外显子组测序(whole-exome sequencing,WES)分析其致病基因,并采用Sanger测序验证。利用Alphafold2、AntheProt及DOG.2.0.1等生物信息学软件分析突变蛋白在三维结构、二级结构和理化性质方面的改变。此外,本研究基于人类基因突变数据库总结了KS患者中组蛋白甲基转移酶2D(histone-lysine N-methyltransferase 2D,KMT2D)基因突变的分布特点。结果该患者表现为典型的KS特殊面容、先天性腭裂、第五指畸形、先天缺牙、肾发育不良和肾积水。WES结果显示该患者携带KMT2D基因新发双突变,即c.[1166A>C;1167dupC](NM_003482),且二者位于同一等位基因上(顺式);以上结果均经等位基因特异性PCR证实。生物信息学分析表明,与野生型KMT2D蛋白相比,突变蛋白p.Y389S、p.V390Rfs*26构象中增加了3个α-螺旋,减少了1个β-转角和1个β-折叠,丢失了C端FYRN、FYRC、SET、PostSET结构域。结论本研究在KS患者中发现了KMT2D基因的新发双突变,且位于同一等位基因,扩大了KMT2D基因的突变谱,为KS的遗传易感性咨询、产前诊断以及早期治疗提供了证据。Objective To screen the candidate genes in a patient with Kabuki syndrome(KS),providing basis for genetic counseling,prenatal screening,prenatal diagnosis and facilitating early treatment.Methods This study included a 16-year-old female KS patient born of non-consanguineous Chinese parents who presented to Department of Orthognathic&Cleft Lip and Palate Plastic Surgery,School and Hospital of Stomatology,Wuhan University.Genomic DNA was extracted from the peripheral blood of the subjects and analyzed by whole-exome sequencing(WES).Sanger sequencing was performed to validate the mutation in the candidate gene.The conformational and physicochemical changes of the mutant were analyzed by Alphafold2,Antheprot and DOG.2.0.1,respectively.Distribution of KMT2D mutations in patients with KS was analyzed based on the Human Gene Mutation Database Results The proband manifested a typical KS facial gestalt,congenital cleft palate,fifth finger deformity,hypodontia,renal hypoplasia and hydronephrosis.Two de novo mutations c.[1166A>C;1167dupC](NM_003482)in cis on the same allele in the KMT2D gene were identified by WES and confirmed by allele-specific PCR.Bioinformatics analysis showed that three moreα-helixes were added,and a(β-)turn and a(β-)sheet were reduced in KMT2D p.Y389S,p.V390Rfs*26 compared with the wild type.Meanwhile,the interceptive mutant-KMT2D protein p.V390Rfs*26 lost all four domains(FYRN domain,FYRC domain,SET domain,and PostSET domain),which may cause functional disabilities.Conclusions Our study is the first to identify two novel and de novo KMT2D mutations in cis on the same allele in a KS patient and extends the KMT2D mutation spectrum of KS,providing evidence for genetic susceptibility counseling,prenatal screening and diagnosis,and early treatment of KS.

关 键 词：突变 歌舞伎面谱综合征 KMT2D基因 全外显子组测序 等位基因特异性PCR 生物信息学分析 

分 类 号：R782.2[医药卫生—口腔医学]