用新一代外显子捕获测序技术诊断眼皮肤白化病Ⅲ型一例北大核心CSCD

目的对一例疑为眼皮肤白化病的患儿进行临床和遗传学分析。方法对患儿进行临床检查,提取患儿及其父母基因组DNA,采用新一代外显子目标区域捕获测序技术对患儿进行基因突变分析,并对疑似致病性突变进行患儿及其父母的Sanger测序验证及生物信息学预测。结果患儿歪头视物,视力低下,伴有双眼水平冲动型眼球震颤,毛发棕黄色。基因测序显示患儿TYRP1基因存在c．1214C〉A（P．T405N）和c．1333dupG杂合突变,分别遗传自其母亲和父亲。生物信息学预测为致病性突变。结论患儿为Ty尺纠基因复合杂合突变引起的眼皮肤白化病Ⅲ型,TYRP1复合杂合突变致病的病例尚未见报道。     

一例Nicolaides-Baraitser综合征的临床与遗传学分析

目的探讨1例表现为癫痫、语言发育迟缓、智力发育轻度迟缓的女性患儿的遗传学病因。方法采集患儿及其父母的外周血样并提取基因组DNA,应用高通量测序技术对患儿进行检测,对疑似致病变异进行Sanger测序验证及生物信息学分析。结果测序结果显示患儿SMARCA2基因存在c.3592 G>A(p.V1198M)杂合变异,生物信息学分析预测其为致病性;在患儿父母的外周血DNA中未发现相同的变异。结论该患儿被确诊为SMARCA2基因杂合变异所致的Nicolaides-Baraitser综合征。     

一例慢通道先天性肌无力综合征的临床与遗传学分析

目的对1例临床表现为竖头不稳、四肢肌张力低下的女性患儿进行遗传学分析,明确其遗传学病因。方法对患儿进行临床检查,采集患儿及其父母和姐弟外周血并提取基因组DNA,应用二代测序技术对患儿进行检测,对疑似致病性变异进行患儿及其父母的Sanger测序验证及生物信息学分析预测。结果基因测序显示患儿CHRND基因存在c.354C>A(p.N118K)杂合变异,未在其父母及姐弟外周血中发现该变异;生物信息学分析预测为可疑致病性变异。文献检索发现与已报道病例表型极为相似。结论该患儿确诊为CHRND基因杂合变异引起的慢通道先天性肌无力综合征3A型,这在国内尚未见报道,二代测序为该病的诊断提供了强有力的工具。     

一例NEDD4L基因变异引起脑室旁结节状灰质异位7型患儿的临床与遗传学分析

目的对1例临床表现为全面发育迟缓、智力低下、腭裂、癫痫及四肢肌张力低下的患儿进行全外显子组测序分析,以明确其遗传学病因。方法抽取患儿及其父母外周血,提取全基因组DNA,应用二代测序技术对全外显子组基因进行变异检测、生物信息学预测分析及Sanger测序验证。结果测序结果显示患儿NEDD4L基因发生c.2117T>C(p.Leu706Pro)杂合变异,经Sanger验证患儿父母未检出该变异,为一新发变异。根据美国医学遗传学与基因组学学会(ACMG)的指南预测c.2117T>C为疑似致病性变异。结论NEDD4L基因c.2117T>C(p.Leu706Pro)变异可能为患儿的遗传学病因。     

高通量测序确诊一例ASXL3基因变异所致的Bainbridge-Ropers综合征

目的对1例表现为精神发育迟滞、语言运动发育迟缓的患儿进行临床及遗传学分析。方法对患儿进行常规染色体G显带核型以及高通量测序分析,对疑似致病变异进行Sanger测序验证和生物信息学分析。结果患儿ASXL3基因存在c.4090G>T(p.Gly1364X)杂合变异,其父母均未携带相同变异,为新生变异。结论ASXL3基因c.4090G>T(p.Gly1364X)变异可能是患儿的遗传学病因。     

利用全外显子测序技术发现BTK基因新生突变

目的利用全外显子测序技术,对疑似X-连锁无丙种球蛋白血症患儿及父母进行测序,发现致病基因突变并明确临床诊断,探讨基因型与临床表型之间的关系及分子诊断的意义。方法提取疑似X-连锁无丙种球蛋白血症患儿及其父母外周血,应用全外显子组捕获高通量测序筛查患儿及父母基因组DNA。通过生物信息学分析,结合dbSNP、千人基因组、ExAC、gnomAD数据库分析变异频率,确定突变位点,用Sanger测序法进行验证。结果通过全外显子测序,在患儿BTK基因中找到一个新发错义杂合突变c.1781GA(p.G594E),该位点位于已报道的热点位置,其父母此位点为正常基因型。结合临床表型和基因检测结果,该患儿被确诊为X-连锁无丙种球蛋白血症。结论本研究明确了X-连锁无丙种球蛋白血症临床表型和该BTK突变位点的相关性。通过全外显子测序技术成功鉴定了BTK基因的突变,强调了该技术在儿童先天性免疫缺陷病的明确诊断和遗传咨询中的实用性     

一例母系嵌合的Nicolaides-Baraitser综合征患儿的临床特征及基因变异分析

目的探讨1例表现为全面发育迟缓、肝功能异常、先天性心脏病、大脑畸形的患儿的基因检测结果, 并分析候选变异的致病性。方法采集患儿及父母外周血标本, 提取基因组DNA, 进行全外显子组高通量测序, 对候选变异进行Sanger测序验证及生物信息学分析。结果基因检测结果提示患儿SMARCA2基因存在c.2002G>T(p.Glu668Ter)杂合变异, 生物信息学分析提示可能致病变异, 患儿母亲的外周血基因组DNA中, 检测到低比例的嵌合变异, 高精度定点检测示变异比例为0.054(246/4 549)。结论该患者被诊断为SMARCA2基因变异引起的Nicolaides-Baraitser综合征, 其母存在低比例的嵌合变异。     

新发现Leber先天性黑矇患者复合杂合突变位点c.1831T>C/c.2172T>A

目的:报告一例散发Leber先天性黑矇(LCA)家系的致病基因复合杂合突变位点c.1831TC/c.2172TA。方法:收集LCA患儿临床和家系资料,采集该家系成员患儿及其父母外周静脉血,提取基因组DNA,先行目标区域捕获测序筛查已知的眼科遗传病相关基因,再利用生物信息学分析获取候选基因,最后经Sanger法测序验证及对突变位点进行分子生物信息学分析。结果:高通量测序筛查结果证实患儿CRBI基因上存在复合杂合突变(c.1831TC,p.S611P;c.2172TA,p.Y724X)。c.2172TA为无义突变,具有明显的致病性。Anthe_2000软件分析p.S611P突变未引起蛋白二级结构和疏水性明显变化。结论:CRBI基因的复合杂合突变(c.1831TC,c.2172TA)可能导致LCA8型的发生。     

一例先天性角化不良患儿的基因变异研究

目的对一例疑似为先天性角化不良的患儿进行临床和遗传学分析。方法对患儿进行临床检查,提取患儿及其父母基因组DNA,采用新一代外显子目标区域捕获测序技术对患儿进行基因变异分析,并对疑似致病性变异对患儿及其父母进行Sanger测序验证及生物信息学预测。结果患儿临床主要表现为指趾甲营养不良、皮肤色素沉着、口腔黏膜白斑,贫血、血小板减少、粒细胞减少。测序结果显示,患儿DKC1基因第12外显子的c.1213A>C变异(p.T405P),患儿母亲为同一位点的杂合变异。同时检测到患儿TERT基因中第12外显子的c.2915G>A变异(p.R972H),患儿父亲为c.2915G>A杂合变异携带者。结论DKC1基因第12外显子的c.1213A>C变异和TERT基因中第12外显子的c.2915G>A变异可能是导致该患儿先天性角化不良发病的分子病因。     

SYNGAP1基因移码变异所致精神发育迟滞患儿1例的遗传学分析

目的探讨1例精神发育迟滞患儿的遗传学病因。方法选取2020年8月6日于广州中医药大学附属南海妇产儿童医院就诊的1例精神发育迟泄患儿为研究对象。用全外显子组测序技术对患儿及其父母进行变异筛查, 结合临床资料分析可能的致病变异, 并通过Sanger测序进行验证。结果基因测序提示患儿携带SYNGAP1基因杂合移码变异c.995₁002delAGACAAAA(p.Asp332AlafsTer84), 其父母未携带相同变异。结论 SYNGAP1基因c.995₁002delAGACAAAA(p.Asp332AlafsTer84)移码变异可能是患儿精神发育迟滞的遗传学原因。上述发现丰富了SYNGAP1基因的变异谱, 为患儿的诊断和治疗提供了依据。     

The first missense mutation of NHS gene in a Tunisian family with clinical features of NHS syndrome including cardiac anomaly

Nance-Horan Syndrome (NHS) or X-linked cataract-dental syndrome is a disease of unknown gene action mechanism, characterized by congenital cataract, dental anomalies, dysmorphic features and, in some cases, mental retardation. We performed linkage analysis in a Tunisian family with NHS in which affected males and obligate carrier female share a common haplotype in the Xp22.32-p11.21 region that contains the NHS gene. Direct sequencing of NHS coding exons and flanking intronic sequences allowed us to identify the first missense mutation (P551S) and a reported SNP-polymorphism (L1319F) in exon 6, a reported UTR-SNP (c.7422 C>T) and a novel one (c.8239 T>A) in exon 8. Both variations P551S and c.8239 T>A segregate with NHS phenotype in this family. Although truncations, frame-shift and copy number variants have been reported in this gene, no missense mutations have been found to segregate previously. This is the first report of a missense NHS mutation causing NHS phenotype (including cardiac defects). We hypothesize also that the non-reported UTR-SNP of the exon 8 (3'-UTR) is specific to the Tunisian population.     

Oculo-cerebro-renal Lowe syndrome: clinical, biochemical and molecular studies in a Moroccan patient

The oculo-cerebro-renal syndrome of Lowe is a rare X-linked disorder, caused by the inositol biphosphate 5-phosphatase deficiency, localized to the Golgi complex. Several mutations were reported in patient's OCRL gene leading to enzyme deficiency. We report a Moroccan case of OCRL syndrome of Lowe with a neo mutation in exon 10. The patient aged of 19 months was referred to our medical centre because of a psychomotor retardation. He had a medical history of eye abnormalities including cataract and bilateral glaucoma, diagnosed when he was 5 weeks old. Cataract has been treated after chirurgical therapy but ocular hypertonia persisted. Physical examination revealed an axial hypotonia and walking difficulties. Laboratory tests revealed a moderate acidosis (20 mmol/L), a slight decrease of serum phosphate level (24 mg/L) and an increased serum phosphatase activity. Further studies showed mild proteinuria, urinary bicarbonates loosing and generalised hyperaminoaciduria. Based on both clinical and biological data, Lowe syndrome has been suggested. In this context, molecular investigation has been performed using dHPLC/sequencing techniques which allow identifying an original mutation c.776T>C (p.Phe259Ser), localized on the exon 10 of the OCRL gene. The mutation was not found in the probant's mother suggesting a neo mutation. Lowe syndrome is a rare hereditary X-linked disorder resulting from a variety of heterogeneous mutations of OCRL gene. Indeed, numerous mutations have been reported, variations were noted concerning their localization as well as their type. To our knowledge, this is the first report of the neo mutation c.776T>C of OCRL gene and the first published case report of the Lowe syndrome in a Moroccan patient.     

The first case of X-linked Alpha-thalassemia/mental retardation (ATR-X) syndrome in Korea

Mutation of the ATRX gene leads to X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome and several other X-linked mental retardation syndromes. We report the first case of ATR-X syndrome documented here in Korea. A 32-month-old boy came in with irritability and fever. He showed dysmorphic features, mental retardation and epilepsy, so ATR-X syndrome was considered. Hemoglobin H inclusions in red blood cells supported the diagnosis and genetic studies confirmed it. Mutation analysis for our patient showed a point mutation of thymine to cytosine on the 9th exon in the ATRX gene, indicating that Trp(C), the 220th amino acid, was replaced by Ser(R). Furthermore, we investigated the same mutation in family members, and his mother and two sisters were found to be carriers.     

A novel missense mutation in the NDP gene in a child with Norrie disease and severe neurological involvement including infantile spasms

Norrie disease (ND) is a rare X-linked recessive disorder characterized by congenital blindness and in some cases, mental retardation and deafness. Other neurological complications, particularly epilepsy, are rare. We report on a novel mutation identified in a patient with ND and profound mental retardation. The patient was diagnosed at the age of 6 months due to congenital blindness. At the age of 8 months he developed infantile spasms, which were diagnosed at 11 months as his EEG demonstrated hypsarrhythmia. Mutation analysis of the ND gene (NDP) of the affected child and his mother revealed a novel missense mutation at position c.134T > A resulting in amino acid change at codon V45E. To the best of our knowledge, such severe neurological involvement has not been previously reported in ND patients. The severity of the phenotype may suggest the functional importance of this site of the NDP gene.     

Localization of MRX82: a new nonsyndromic X-linked mental retardation locus to Xq24-q25 in a Basque family

Clinical and molecular studies are reported on a Basque family (MRX82) with nonsyndromic X-linked mental retardation (XLMR) in five affected males. A total of 38 microsatellite markers were typed. The XLMR locus has been linked to DXS8067, DXS1001, DXS425, DXS7877, and DXS1183 with a maximum LOD score of 2.4. The haplotype studies and multipoint linkage analysis suggest a localization of the MRX82 locus to an interval of 7.6 Mb defined by markers DXS6805 and DXS7346, in Xq24 and Xq25, respectively. No gene contained in this interval has been so far associated with nonsyndromic mental retardation, except for GRIA3, disrupted by a balanced translocation in a female patient with bipolar affective disorder and mental retardation. However, the search for mutations of this gene did not showed a pathogenic mutation in the present family. Given that there are other eight MRX families overlapping this interval, none of them with known mutation, we conclude that at least one new gene responsible for nonsyndromic mental retardation is located in this region.     

Novel compound heterozygous mutation of MLYCD in a Chinese patient with malonic aciduria

A 3-year-old Chinese boy presented with prominent clinical features of malonic aciduria, including developmental delay, short stature, brain abnormalities and massive excretion of malonic acid and methylmalonic acid. Molecular characterization by DNA sequencing analysis and multiplex ligation-dependent probe amplification of the MLYCD gene revealed a heterozygous mutation (c.920T>G, p.Leu307Arg) in the patient and his father and a heterozygous deletion comprising exon 1 in the patient and his mother. The missense mutation (c.920T>G) was not found in 100 healthy controls and has not been reported previously. Our findings expand the number of reported cases and add a novel entry to the repertoire of MLYCD mutations.     

Mutation analysis of seven patients with Waardenburg syndrome北大核心CSCD

Objective: To perform genetic analysis for 7 patients with Waardenburg syndrome. Methods: Potential mutation of MITF, PAX3, SOX10 and SNAI2 genes was screened by polymerase chain reaction and direct sequencing. Functions of non-synonymous polymorphisms were predicted with Polyphen2 software. Results: Seven mutations, including c. 649-651delAGA (p. R217del), c. 72delG (p. G24fs), c. 185T>C (p. M62T), c. 118C>T (p. Q40X), c. 422T>C (p. L141P), c. 640C>T (p. R214X) and c. 28G>T (p. G43V), were detected in the patients. Among these, four mutations of the PAX3 gene (c. 72delG, c. 185T>C, c. 118C>T and c. 128G>T) and one SOX10 gene mutation (c. 422T>C) were not reported previously. Three non-synonymous SNPs (c. 185T>C, c. 128G>T and c. 422T>C) were predicted as harmful. Conclusion: Genetic mutations have been detected in all patients with Waardenburg syndrome. © 2016, West China University of Medical Sciences. All rights reserved.