一个 PCDH15基因变异所致的Usher综合征家系的遗传学分析及产前诊断

目的:对1个Usher综合征家系的临床特征及基因变异进行分析,明确其遗传病因。方法:对家系中患儿进行全外显子测序,就发现的可疑致病变异用Sanger测序法对患儿及其父母进行检测,明确先证者病因后,进一步对家系中的胎儿进行产前诊断。结果:测序结果显示先证者 PCDH15基因(NM_033056)存在c.17_...     

心-面-皮肤综合征MAP2K1基因新发变异一例

目的探讨MAP2K1基因变异所致的心-面-皮肤综合征(cardio-facio-cutaneous syndrome,CFCS)基因型与表型的对应关系。方法收集先证者及其父母的外周血样,提取DNA,采用全外显子组测序对先证者进行检测,用Sanger测序对先证者及父母进行验证。结果先证者为1岁8个月的男性,临床表现为身材矮小、精神运动发育迟缓、大头畸形、特殊面容、先天性心脏病等多发异常。全外显子组测序发现其携带MAP2K1基因c.389A>G(p.Tyr130Cys)杂合错义变异,Sanger测序证实其为新发变异。根据ACMG/AMP指南,判定为致病性变异。结论本例患儿存在明显的行为异常、食欲佳、三尖瓣返流,有别于既往报道的病例,因此丰富了MAP2K1基因变异所导致的CFCS的临床表型谱。     

全外显子测序检测一例Tp63基因变异导致的缺指(趾)-外胚层发育不良-唇腭裂综合征

目的对1例疑似缺指(趾)-外胚层发育不良-唇腭裂综合征男性引产胎儿进行基因变异检测。方法采集先证者皮肤标本和其父母的血液标本提取DNA进行全外显子测序筛选可疑致病性变异位点,Sanger测序对可疑致病位点进行验证。结果检测到先证者中"63基因c.673OT杂合错义变异,其父母均为野生型,该变异曾被报道导致手裂/足裂畸形。结论Tp63基因的c.673OT杂合错义变异可能是该先证者的发病原因。本研究结果为该病的遗传咨询和分子诊断提供了依据,并扩大了该变异导致的临床表现谱。     

一个常染色体显性智力低下1型家系的MBD5基因新变异

目的对1例智力、运动发育落后、语言发育严重受损、面部畸形合并癫痫的患儿及其家系成员进行基因变异分析。方法应用全外显子分析技术对先证者进行致病变异筛查,结合先证者的表型确定候选致病位点,应用Sanger测序对先证者、父母及其他家系成员进行变异位点验证。结果先证者携带MBD5基因c.2217delT(p.F739Lfs*6)框移变异,文献未见报道,来源于母亲,经家系验证,其兄携带相同变异且具有相似的表型,其母年幼时语言表达能力差,学习成绩差,可做家务,无抽搐病史。结论发现一个MBD5基因新的致病变异,丰富了MBD5基因变异谱,家系研究发现该基因变异存在表现度差异。本研究结果为该家系的病因诊断和产前诊断提供了依据。     

MCCC2基因变异致3-甲基巴豆酰辅酶A羧化酶缺乏症患儿的家系分析

目的对1例临床疑诊3-甲基巴豆酰辅酶A羧化酶缺乏症(3-methylcrotonyl-coenzyme A carboxylase deficiency,MCCD)患儿及其父母进行基因变异分析,寻找该家系的致病变异,为临床诊断提供分子遗传学依据。方法抽提先证者及其父母的外周血基因组DNA,应用全外显子组基因测序技术对疑似为MCCD疾病的先证者进行致病基因筛查。根据高通量测序结果,对先证者及其父母进行变异位点的Sanger测序验证分析。应用计算机软件预测变异位点氨基酸进化保守性和变异可能导致的蛋白质结构和功能变化,分析变异位点的性质。结果Sanger测序结果显示先证者为MCCC2基因c.1342G>A(p.Gly448Ala)纯合错义变异,为未报道过的新变异。先证者母亲为c.1342G>A(p.Gly448Ala)杂合变异携带者,父亲未检测到该变异。用PolyPhen-2和Mutation Taster软件预测该变异为致病性,变异区域序列在不同物种间高度保守。根据美国医学遗传学与基因组学学会遗传变异分类标准与指南,MCCC2基因c.1342G>A(p.Gly448Ala)变异判定为可能致病性变异(PM2+PP2~PP5)。结论先证者MCCC2基因c.1342G>A(p.Gly448Ala)纯合错义变异是其分子发病机制,基因变异分析有助于明确临床诊断。     

线粒体DNA缺失综合征9型一例临床特点和SUCLG1基因变异分析

目的报道1例线粒体DNA缺失综合征9型患儿的临床特征和SUCLG1基因变异特点。方法采集患儿和父母外周血,提取基因组DNA,采用高通量测序的方法在该患儿DNA中检测到SUCLG1基因变异,再用Sanger测序的方法进行验证。结果高通量测序(next generation sequencing,NGS)检测到患儿存在为SUCLG1基因c.826-2AG纯合变异。Sanger测序验证发现患儿存在为SUCLG1基因c.826-2AG纯合变异,而其父母均为c.826-2AG杂合变异。结论先证者明确诊断为SUCLG1基因变异导致的线粒体DNA缺失综合征9型。为后续治疗和家系其他可疑成员遗传咨询提供基础。     

Xq13.1缺失致少汗性外胚层发育不良的表型及遗传学分析

目的探讨1例Xq13.1缺失致EDA基因部分缺失的少汗性外胚层发育不良的临床表型及遗传学特点。方法分析1例少汗性外胚层发育不良患儿的临床资料,并进行染色体核型、家系全外显子组测序(trio-whole exome sequencing,trio-WES)、基因组拷贝数变异检查(copy number variations,CNV-seq),对分析得到的可疑致病位置进行父母验证,明确异常基因变异来源。结果先证者,男,7岁8月龄。头发稀少卷曲,眉毛浅淡稀疏,皮肤干燥,自幼易发热,少汗/无汗,牙齿尖、稀疏/部分缺失,鞍状鼻,前额突出,耳廓内收,癫痫发作。先证者常规染色体核型检查、全外显组测序未见异常;基因组拷贝数变异检查结果显示Xq13.1q13.1(chrX:g.68796566-69138468)位置存在约341.90 kb缺失,包含有EDA基因部分片段。经验证缺失区域来自先证者母亲,其临床表型为毛发正常,皮肤稍干燥,牙齿稀疏、脱落、钉状牙,基因组拷贝数变异检查检测到Xq13.1q13.1(chrX:g.68836154-69078250)位置存在约242.10 kb杂合缺失。结论先证者及其母亲均存在Xq13.1缺失致EDA基因部分片段缺失,母亲临床表型较轻,先证者临床症状较重,符合X连锁隐性遗传少汗性外胚层发育不良发病特点,EDA基因部分缺失很可能是导致先证者出现异常临床表型的原因。     

一个先天性小眼畸形家系的全外显子组测序分析及产前诊断

目的分析1个先天性小眼畸形家系的临床表型及遗传学病因。方法应用高通量测序技术对先证者及其父母进行全外显子组测序,筛选候选致病位点,对其家系进行Sanger测序验证,并通过羊水穿刺和Sanger测序为先证者母亲提供产前诊断。结果全外显子组测序和Sanger测序发现家系中的3例患者均携带OTX2基因c.289C>T(p.R97*)杂合变异,先证者母亲亦携带该变异,但无小眼畸形。先证者的父亲、舅母和胎儿未携带上述变异。结论OTX2基因c.289C>T(p.R97*)杂合变异很可能是该家系的发病原因。上述诊断将有助于该家系的遗传咨询和产前诊断。     

四个遗传性耳聋家系的TMC1基因变异分析及产前诊断

目的对4个耳聋家系进行遗传性耳聋基因变异的筛查,为家系遗传咨询与产前诊断提供依据。方法应用二代测序技术对家系先证者进行耳聋基因检测,并对可疑基因变异采用Sanger双向测序对先证者及家系成员进行验证,确定可疑致病变异后,对3个家系高危胎儿进行产前诊断。结果家系1先证者检测到TMC1基因c.100C>T(p.R34X)和c.642+4A>C复合杂合变异,家系2先证者检测到TMC1基因c.582G>A(p.W194X)和c.589G>A(p.G197R)复合杂合变异,家系3先证者检测到TMC1基因c.1396_1398delAAC和c.1571T>C(p.F524S)复合杂合变异,家系4先证者检测到TMC1基因c.2050G>C(p.D684H)纯合变异,4个家系先证者父母均为携带者,其中c.642+4A>C、c.1571T>C(p.F524S)变异位点既往未见报道;产前诊断结果显示3个家系胎儿均不是患者,出生后随访至2019年9月,听力未见异常。结论TMC1基因变异是4个耳聋家系的可能致病原因,分子生物学的发现增加了对TMC1基因功能的认识并丰富了人类基因变异数据库,为家系遗传咨询和产前诊断提供了依据。     

两个Coffin-Siris综合征家系的 ARID1B基因变异分析

目的:通过对两个Coffin-Siris综合征家系先证者的临床表征及基因变异分析,揭示其可能的遗传发病机制,为家系的遗传咨询提供依据。方法:应用全外显子组测序技术对两例先证者进行致病原因筛查,结合临床表型确定可能致病的候选基因,用Sanger测序法对先证者及其家系成员进行变异验证。结果:WES检测结果显示家系1先证者 ...     

Analysis of CNTNAP1 gene variants in a Chinese pedigree affected with lethal congenital contracture syndrome type 7CSCD

Objective To explore the genetic basis for a couple who had developed polyhydramnios during three pregnancies and given birth to two liveborns featuring limb contracture, dyspnea and neonatal death. Methods Whole-exome sequencing (WES) was carried out on fetal tissue and peripheral blood samples from the couple. Suspected variants were verified by Sanger sequencing. Results The fclus was found to harbor homozygous nonsense c. 37180T (p. Argl240Ter) variants of theCNTNAPI gene, which were respectively inherited from its mother and father. The variant was unreported previously. According to the guidelines of the American College of Medical Genetics and Genomics, the variant was predicted to be pathogenic (PVS1 + PM2 + PP4). Conclusion The novel homozygous nonsense variants of the CNTN API gene probably underlay the lethal congenital contracture syndrome type 7 (LCCS7) in this pedigree. Above finding has enabled genetic counseling and prenatal diagnosis for the family. © 2022 West China University of Medical Sciences. All rights reserved.     

Genotype-epigenotype-phenotype correlations in females with frontometaphyseal dysplasia

Frontometaphyseal dysplasia (FMD) belongs to a group of overlapping skeletal dysplasias, the common molecular basis of which are mutations of FLNA, the gene encoding filamin A. The nature of the mutation has been considered the major determinant of the phenotype within this group that comprises the otopalatodigital syndromes (OPD1, OPD2) and Melnick-Needles syndrome besides FMD. However, to date the molecular pathomechanisms are not well understood. In FMD only few FLNA mutations have been reported which do not cluster in a specific region of the protein. We report on a novel de novo mutation 5182G --> T in exon 31 of the FLNA gene in a girl with manifestations of FMD and OPD1. This mutation is predicted to lead to the exchange of a highly conserved glycine residue at position 1,728 by cysteine (G1728C) in repeat 15 of the filamin A rod domain. In a second family with FMD, we identified a known mutation (S1186L) in a mother and her son. In contrast to most previous reports on manifesting females or carriers of the FLNA-related skeletal dysplasias, the affected females presented here showed only mild to moderate skewing of X-inactivation against the mutant allele. Our data may indicate that in females, genotype-phenotype correlation between certain FLNA mutations and OPD1 and FMD, respectively, is less strict than previously assumed. We propose that X-inactivation is an important epigenetic modifier of the phenotype in females with the FLNA-related skeletal dysplasias.     

Frontometaphyseal dysplasia: mutations in FLNA and phenotypic diversity

Frontometaphyseal dysplasia is an X-linked trait primarily characterized by a skeletal dysplasia comprising hyperostosis of the skull and modeling anomalies of the tubular bones. Extraskeletal features include tracheobronchial, cardiac, and urological malformations. A proportion of individuals have missense mutations or small deletions in the X-linked gene, FLNA. We report here our experience with comprehensive screening of the FLNA gene in a group of 23 unrelated probands (11 familial instances, 12 simplex cases; total affected individuals 32) with FMD. We found missense mutations leading to substitutions in the actin-binding domain and within filamin repeats 9, 10, 14, 16, 22, and 23 of filamin A in 13/23 (57%) of individuals in this cohort. Some mutations present with a male phenotype that is characterized by a severe skeletal dysplasia, cardiac, and genitourinary malformations that leads to perinatal death. Although no phenotypic feature consistently discriminates between females with FMD who are heterozygous for FLNA mutations and those in whom no FLNA mutation can be identified, there is a difference in the degree of skewing of X-inactivation between these two groups. This observation suggests that locus heterogeneity may exist for this disorder.     

一例肾单位肾痨2型胎儿的产前超声表型及遗传学分析

目的对1例既往有胎儿双肾体积增大及羊水过少孕育史,本次妊娠16周余超声提示为双侧多囊性肾发育不良及羊水过少的引产胎儿行肾脏病理及分子遗传学检查,明确其病因,并为该家系的产前诊断和遗传咨询提供依据。方法对胎儿行超声检查明确其肾脏形态学改变,经遗传咨询后胎儿父母决定终止妊娠,取引产胎儿肾脏组织行病理学检查,通过目标区域捕获二代测序(next generation sequencing,NGS)对胎儿行遗传性肾脏疾病基因变异筛查,对胎儿及其父母行可疑致病基因变异位点Sanger测序验证。结果胎儿肾脏组织学检查提示为多囊性改变,未见正常的肾脏结构、肾皮质或髓质。NGS和PCR等检查明确胎儿携带INVS基因c.100+1G>A杂合变异和第3外显子杂合缺失,均为致病性变异,分别来自其母亲和父亲。结论对一个双侧多囊性肾发育不良引产胎儿明确诊断为肾单位肾痨2型(typeⅡnephronophthisis,NPHP2),对该家庭再次生育提供了精准的指导。NPHP2疾病的基因诊断在国内鲜有报道,本研究结果加强了对该类疾病临床表现和遗传学病因的认识。     

A novel filamin A D203Y mutation in a female patient with otopalatodigital type 1 syndrome and extremely skewed X chromosome inactivation

Otopalatodigital syndrome type 1 (OPD1) [OMIM 311300] is an X-linked dominant multiple congenital anomalies disease mainly characterized by a generalized skeletal dysplasia, mild mental retardation, hearing loss, cleft palate, and typical facial anomalies. OPD1 belongs to a group of X-linked skeletal dysplasias known as oto-palato-digital syndrome spectrum disorders that also include OPD2, Melnick-Needles syndrome (MNS), and frontometaphyseal dysplasia (FMD). Recently, it has been demonstrated that mutations in the gene encoding the cytoskeletal protein Filamin A (FLNA) are responsible for this group of clinically overlapping human syndromes. We present the phenotypic and molecular data of a sporadic female patient clinically diagnosed with an OPD1 syndrome who carried a novel FLNA point mutation resulting in an Asp203Tyr substitution in the actin-binding domain of the protein. X-inactivation analyses demonstrated an extremely skewed pattern towards her maternal chromosome. Our results add to the molecular spectrum of the oto-palato-digital related syndromes and contribute to the delineation of phenotype-genotype correlation in this group of X-linked skeletal disorders.     

六个成骨不全家系的临床表型分析及基因变异检测

目的分析6个成骨不全家系的临床表型并明确其致病变异,为遗传咨询及产前诊断提供依据。方法收集6个家系的临床资料以及外周血或引产组织样本,应用二代测序(next generation sequencing,NGS)技术对先证者的全部基因进行检测,用PCR反应扩增检出的变异位点,之后进行Sanger测序。在6个家系的所有成员以及100名健康对照中对检测到的变异位点进行验证。结果家系1的先证者及其女儿携带COL1A1基因c.1976G>C杂合变异,家系2~6的先证者分别携带COL1A2基因c.2224G>A、COL1A1基因c.2533G>A、COL1A2基因c.2845G>A、COL1A1基因c.2532_2540delCGGACCCGC以及COL1A2基因c.1847G>A杂合变异。先证者的双亲均未携带相应变异,在100名健康对照中均未检测到上述变异。结论6个成骨不全家系的致病原因可能均为COL1A1/2基因的变异。新发现的变异丰富了成骨不全症的表现型-基因型数据库,并为这些家系的遗传咨询及产前诊断提供了依据。     

一例OCRL基因外显子重复变异所致的眼脑肾综合征患儿的临床及遗传学分析

目的探讨1例表现为先天性白内障、脑发育迟缓、蛋白尿的男性患儿的遗传学病因。方法收集患儿的临床资料,采集患儿及其正常表型的亲代的外周血样,提取基因组DNA,应用高通量测序法筛查OCRL基因的变异,并用定量PCR法进行验证。通过变异序列分析和PubMed检索,预测候选变异的致病性。结果患儿曾接受先天性白内障手术,脑发育迟缓,脑部成像显示脑沟裂增宽、双侧额颞部蛛网膜下腔增宽、脑室后角旁白质髓鞘化不良等,此外有蛋白尿及双肾弥漫性回声。患儿X染色体OCRL基因第5~16外显子存在重复变异。患儿母亲为该变异的携带者,父亲未携带。结论OCRL基因第5~16外显子重复变异是该患儿的发病原因。由OCRL基因外显子重复所致的眼脑肾综合征尚无文献报道。鉴于眼脑肾综合征临床表现的异质性,基因检测对于该病的确诊具有重要的意义。     

NDUFS1基因复合杂合变异致线粒体呼吸链复合物Ⅰ缺陷一家系

目的探讨1个疑似线粒体病家系的遗传学病因。方法收集患者及其家系成员的临床资料;抽取家系成员外周血,应用二代测序进行家系全外显子组、基因组拷贝数变异和线粒体基因组检测,对候选基因变异位点进行Sanger测序验证。结果全外显子组家系检测发现患儿存在NDUFS1基因父源c.64C>T(p.R22X)和母源c.845A>G(p.N282S)复合杂合变异,二者均可能导致蛋白功能丧失。基因组拷贝数变异和线粒体基因组检测未发现致病变异。结论疑似线粒体病的患儿可能缺少特异性的临床表型,包含线粒体DNA检测在内的综合性基因检测策略有助于及早明确诊断和治疗干预。     

A founder truncating variant in GDF1 causes autosomal‐recessive right isomerism and associated congenital heart defects in multiplex Arab kindreds

The genetic basis of congenital heart malformations associated with disruption of left–right (L–R) asymmetry is broad and heterogenous, with variants in over 25 genes implicated thus far. Of these, deleterious variants in the Growth/Differentiation Factor 1 (GDF1) gene have been shown to cause heterotaxy with varied complex heart malformations of left–right patterning, in 23 individuals reported to date, either in monoallelic or biallelic state. We report three unrelated individuals exhibiting right isomerism with congenital heart defects, each originating from a consanguineous kindred of Arab‐Muslim descent. Using whole exome sequencing, a shared novel homozygous truncating c.608G > A (p.W203*) variant in the GDF1 gene was revealed as the molecular basis of their disease. Subsequently, targeted sequencing of this variant showed full segregation with the disease in these families, with a total of over 15 reportedly affected individuals, enabling genetic counseling, prenatal diagnosis, and planning of future pregnancies. Our findings further confirm the association of biallelic GDF1 variants, heterotaxy and congenital heart defects of left–right patterning, and expand the previously described phenotypic spectrum and mutational profile. Moreover, we suggest targeted screening for the p.W203* variant in relevant clinical circumstances.