二氮嗪治疗无效的先天性高胰岛素血症3例家系KCNJ11基因突变分析

目的对3例二氮嗪治疗无效的先天性高胰岛素血症患儿及其家系进行KCNJ11基因突变分析，初步探讨中国儿童腺嘌呤核苷三磷酸敏感性钾通道型高胰岛素血症的发病机制。方法以2008年1月至2009年12月我院收治的3例二氮嗪治疗无效的先天性高胰岛素血症患儿及其家系为研究对象，采用聚合酶链反应DNA直接测序法对3例患儿及其亲属进行KCNJ11基因测序分析。结果于第1例患儿及其父亲的KCNJ11基因外显子中分别发现1个703C〉G（Q235E）杂合失活突变，患儿母亲该位点基因型正常（C／C）。未发现第2、3例患儿家系中出现KCNJ11基因突变。结论KCNJ11基因Q235E突变可以导致腺嘌呤核苷三磷酸敏感性钾通道型先天性高胰岛素血症的发生，少数常染色体显性遗传KCNJ11基因突变所致的腺嘌呤核苷三磷酸敏感性钾通道型先天性高胰岛素血症对二氮嗪治疗无效。     

ABCC8基因突变致ATP敏感性钾通道型先天性高胰岛素血症一例家系分析

对1例临床诊断为先天性高胰岛素血症的患儿家系进行ABCC8、内向整流钾通道6.2( KCNJ11)、谷氨酸脱氢酶1(GLUD1)基因突变分析,结果于患儿ABCC8基因第10外显子发现一个1484G＞A杂合失活突变,该突变可导致磺脲类药物受体1(SUR1)蛋白第495位精氨酸残基被谷氨酰氨所取代.患儿父亲携带有同样的杂合突变,但无低血糖表现,故为无症状携带者.患儿母亲该位点基因型正常,提示该患儿携带的突变基因系父系遗传,据此初步推断该患儿胰腺的病理学分型为局灶型.     

伴钙黏蛋白1基因突变的遗传性弥漫型胃癌

遗传性弥漫型胃癌是一种常染色体显性遗传病,以胃弥漫型印戒细胞癌和乳腺小叶癌为特征。该综合征的遗传基础是编码E-钙黏蛋白的钙黏蛋白1( CDH1)基因的胚系突变。该患者为年轻女性,胃体后壁、胃体前壁见印戒细胞癌,外周血行基因二代测序检测显示 CDH1基因第10外显子存在杂合性突变,经多学科协作讨论后,...     

婴儿型低磷酸酶血症组织非特异性碱性磷酸酶基因突变检测

目的 对1例婴儿型低磷酸酶血症患者及其父母进行临床分析和基因突变检测,以探讨该病的致病机制.方法 针对1例罕见的婴儿型低磷酸酶血症患者进行实验室检验及影像学检查.进而提取患儿及其亲属外周血基因组DNA,采用针对组织非特异性碱性磷酸酶ALPL基因调控区及编码区的特异性引物进行PCR扩增,直接对产物进行测序,并对所鉴定的突变在无关人群中进行验证.结果 患儿血碱性磷酸酶水平显著降低,同时存在高钙血症、中度贫血及双肾钙化;骨骼具有佝偻病样改变.ALPL基因测序结果显示患儿为复合杂合突变,同时携带位于第7外显子的c.814C ＞T (p.R272C)错义突变及位于第9外显子的c.1101_1103 delCTC (p.S368 del)碱基缺失突变.临床表现正常的患儿母亲、父亲为杂合子,分别携带c.1101_1103 delCTC (p.S368del)碱基缺失突变及c.814C ＞T (p.R272C)错义突变.该家系符合常染色体隐性遗传,50例无关健康个体验证未发现上述两种突变存在.结论 ALPL基因c.814C＞T(p.R272C)和c.1101_1103 delCTC(p.S368del)突变与该家系婴儿型低磷酸酶血症临床表现密切相关.     

1例1型肢端发育不全的诊断

目的 总结1例肢端发育不全1型患儿临床特征及诊断方法。方法 对1例肢端发育不全患儿临床特征和诊断过程作回顾性分析。结果 患儿主要临床表现为身材矮小、短指（趾）和双下肢不等长。遗传性骨病相关基因测序结果显示，患儿存在PRKAR1A基因第17号外显子c. 1102C>T(p. R368X)杂合突变，其父母均无该位点变异，明确诊断为肢端发育不全1型。结论 肢端发育不全1型患儿临床表现为身材矮小、短指（趾）、双下肢不等长等，遗传学显示PRKAR1A基因第17号外显子存在c. 1102C>T(p. R368X)杂合突变，通过临床表现结合基因检测可明确诊断。     

儿童糖尿病合并佝偻病和白内障1例

该文报道1例以糖尿病合并佝偻病和白内障起病患儿的诊疗经过。患者为12岁10个月男孩, 主因"视物模糊10余天, 易饥多食6 d"入院, 入院后通过芯片捕获高通量测序技术对患儿外周血进行全外显子组检测+线粒体基因组测序, 结果显示患儿脂蛋白受体相关蛋白5(LRP5)基因第23号外显子存在纯合突变, 该基因的编码区4643位的碱基G突变为T(c.G4643T), 为错义突变。该基因通过调控Wnt信号通路, 在骨形成和发病机制中起重要作用, 该通路还可影响胰岛素分泌进而导致血糖异常。LRP5的隐性突变还可导致家族性渗出性玻璃体视网膜病变, 其也与Wnt信号通路有关。该文通过对相关临床表型发病机制的报道研究, 有望对儿童糖尿病合并佝偻病和白内障提出更合适的诊疗方案。     

先天性高胰岛素血症四例ABCC8基因突变分析

先天性高胰岛素血症（congenital hyperinsulinism,CHI）是婴儿持续性、复发性低血糖的主要原因之一,迄今已发现了8种遗传学类型.ATP敏感性钾通道型先天性高胰岛素血症（KATP-CHI）是CHI最严重和最常见的类型,约占CHI患儿的40％ ～ 45％,其中82％的患儿对二氮嗪治疗无效[1-2].ATP结合暗盒蛋白家族C8 （ATP-binding cassette subfamily C8,ABCC8）基因编码的磺脲受体1（SUR1）是CHI最主要的致病基因,迄今已发现了150多种突变[3].其遗传方式多为常染色体隐性遗传,少数为常染色体显性遗传,偶见新生突变.国外研究资料显示不同类型的ABCC8基因突变临床表现有着较大的异质性.本研究运用分子生物学技术对4例CHI患儿家系的ABCC8基因的39个外显子区进行测序,以期揭示CHI的致病机制.     

一个X-连锁肾上腺脑白质营养不良家系的临床特征及致病基因分析

目的对1例以肾上腺皮质功能减低症起病的X-连锁肾上腺脑白质营养不良(X-ALD)患儿及其家系的临床特征、ATP结合盒转运子超家族成员D1(ABCD1)基因突变进行分析。方法纳入1个2代中有2例发病的汉族X-ALD家系,收集该患者家系成员的临床资料,并运用二代测序技术对先证者及其父母、弟弟行ABCD1基因测序分析。结果2例发病患儿均为男性,先证者表现为原发性肾上腺皮质功能减退和神经系统功能异常,大脑白质广泛脱髓鞘改变,血极长链脂肪酸浓度明显升高。先证者弟弟2岁10个月时出现原发性肾上腺皮质功能减低症状,目前无神经系统症状。先证者及其弟弟基因测序结果均显示:ABCD1基因第7号外显子区域(Exon7)存在c.1666C>T杂合突变,经家系验证,该突变遗传自其母亲。结论ABCDl基因c.1666C>T突变可导致肾上腺脑白质营养不良,原发性肾上腺皮质功能减退和神经系统异常为X-ALD典型临床表现。     

一例组织非特异性碱性磷酸酶基因突变所致的围生期致死型低磷酸酶症病例

目的对1例围生期致死型(新生儿型)低磷酸酶症(HPP)患者及其父母进行临床分析及基因突变检测,以期能更好地认识该病。方法对l例罕见的围生期致死型低磷酸酶症患者的临床表现、实验室及影像学检查结果进行总结。提取患儿及其亲属外周血基因组DNA,采用针对组织非特异性碱性磷酸酶(ALPL)基因调控区及编码区的特异性引物进行PCR扩增,直接对产物进行测序分析。结果患儿血碱性磷酸酶水平显著降低,血钙增高;骨骼显示骨软骨发育障碍类疾病样改变。ALPL基因测序结果显示患儿为复合杂合突变,同时携带位于第5外显子及第10外显子上c.346G>A(p.A116T)和c.1171C>T(p.R391C)的错义突变。临床表现正常的父亲、母亲为杂合子,分别携带c.346G>A(p.A116T)和c.1171C>T(p.R391C)的错义突变。该家系符合常染色体隐性遗传。结论围生期致死型HPP死亡率很高,骨骼发育异常、高血钙、血清低碱性磷酸酶在其鉴别诊断中非常重要。     

帕金森病parkin基因的突变分析

目的 探讨中国人帕金森病（PD）中parkin基因第3-7外显子是否存在缺失突变,及其与该病临床特点的关系。方法 采集33例散发性PD和6例家族性PD患者外周血液,提取DNA,通过PCR扩增,琼脂糖凝胶电泳鉴定parkin基因第3-7外显子缺失突变,并结合临床资料分析。结果 33例散发性PD患者中发现2例有第7外显子缺失,1例有第5、7外显子联合缺失,其起病年龄分别为46、48、50岁,6例家族性PD患者中,发现1例有第5外显子缺失,其遗传模式呈常染色体隐性遗传,起病年龄60岁;所有缺失突变患者均有震颤,僵直和运动迟缓,但无异动症。第3、4、6外显子未发现缺失突变,结论 中国散发性和家族性PD患者中存在parkin基因第5、7外显子缺失突变改变。     

先天性心脏病相关HAND1基因新突变研究

目的:研究先天性心脏病(congenital heart disease,CHD)相关HAND1基因新突变。方法:入选CHD患儿136例及健康对照儿童200名,抽提基因组DNA,通过聚合酶链反应测序筛查HAND1基因突变。应用计算机软件评估突变氨基酸的保守性并预测突变的致病性,应用双荧光素酶报告基因分析系统分析突变对HAND1功能的影响。结果:在1例法洛四联征患儿发现1种新的HAND1基因杂合突变,其编码核苷酸序列第389位的胸腺嘧啶突变为鸟嘌呤(c.389TG),相应氨基酸序列的第130位亮氨酸变为精氨酸(p.L130R)。该突变改变了进化上保守的氨基酸序列并被预测为有致病性,功能研究揭示突变型HAND1的转录激活功能显著降低。结论:该HAND1基因功能缺失性新突变可能是CHD的少见分子病因。     

青少年发病的成人糖尿病7型新突变的可能位点

目的通过对一个高度怀疑为青少年发病的成人糖尿病7型(MODY7)家系进行信息收集及基因检测,寻找其基因突变位点,并探讨其临床特点。方法对1例病程20年、长期胰岛素治疗但血糖控制不佳、无酮症倾向、有3代糖尿病家族史的28岁女性患者进行基因检测,发现其携带KLF11基因变异,遂对其家系进行调查,收集家庭成员相关临床资料,并进行致病基因检测。基因检测方法为:首先对先证者采用芯片捕获高通量测序方法寻找致病基因,然后使用Sanger测序技术验证基因突变位点,并对其他家系成员使用Sanger测序技术筛查有无相同基因突变位点。结果该家系共检出2例成员存在KLF11基因杂合突变c.920C>T(编码区第920号核苷酸由胞嘧啶变异为胸腺嘧啶),导致氨基酸改变p.P307L(第307号氨基酸由脯氨酸变异为亮氨酸),为错义突变。这与其临床被诊断为糖尿病相符合。结论本研究的家系为KLF11基因c.920C>T(p.P307L)错义突变导致糖尿病家系,该突变位点可能是MODY7新突变位点。     

Brain dopamine-serotonin vesicular transport disease presenting as a severe infantile hypotonic parkinsonian disorder

Two male siblings from a consanguineous union presented in early infancy with marked truncal hypotonia, a general paucity of movement, extrapyramidal signs and cognitive delay. By mid-childhood they had made little developmental progress and remained severely hypotonic and bradykinetic. They developed epilepsy and had problems with autonomic dysfunction and oculogyric crises. They had a number of orthopaedic problems secondary to their hypotonia. Cerebrospinal fluid (CSF) neurotransmitters were initially normal, apart from mildly elevated 5-hydroxyindolacetic acid, and the children did not respond favourably to a trial of levodopa-carbidopa. The youngest died from respiratory complications at 10 years of age. Repeat CSF neurotransmitters in the older sibling at eight years of age showed slightly low homovanillic acid and 5-hydroxyindoleacetic acid levels. Whole-exome sequencing revealed a novel mutation homozygous in both children in the monoamine transporter gene SLC18A2 (p.Pro237His), resulting in brain dopamine-serotonin vesicular transport disease. This is the second family to be described with a mutation in this gene. Treatment with the dopamine agonist pramipexole in the surviving child resulted in mild improvements in alertness, communication, and eye movements. This case supports the identification of the causal mutation in the original case, expands the clinical phenotype of brain dopamine-serotonin vesicular transport disease and confirms that pramipexole treatment may lead to symptomatic improvement in affected individuals.     

A Novel Pathogenic β-Thalassemia Mutation Identified at Codon 8 (HBB: c.27delG) in a Bangladeshi Family Acquired De Novo

Abstract

In Bangladesh, the practice of β-thalassemia (β-thal) carrier screening and prenatal diagnosis (PND) by β-globin gene sequencing has been initiated to prevent the birth of affected children. The study aimed to describe a novel de novo mutation of the β-globin gene and its clinical implication. Out of 100 Bangladeshi β-thal carrier families, one patient with hematological and clinical features associated with β-thal and her parents were included. Molecular characterizations of β-globin gene mutations were performed by direct sequencing. A novel nucleotide deletion mutation at codon 8 in the first exon of the β-globin gene (HBB: c.27delG) was found in a 1-year-old child of the studied family in a heterozygous state along with common Hb E (HBB: c.79G>A). The mutation caused a frameshift to a new stop codon at codon 18 resulting in a β⁰-thal phenotype. The proband exhibited a β-thal intermedia (β-TI)-like genotype, however, showed β-thal major (β-TM)-like complications and was transfusion-dependent. Her mother had a profile consistent with the Hb E trait, while the father had normal hematological indices. Mutation analyses revealed the mother to be heterozygous for Hb E, while the father had a normal genotype. The novel mutation was assumed to be inherited de novo by the paternity test. The study documented a novel pathogenic mutation in the β-globin gene in a Bangladeshi family by β-globin gene sequencing.     

An Israeli Arab patient with a de novo TNFRSF1A mutation causing tumor necrosis factor receptor-associated periodic syndrome

OBJECTIVE: To investigate genetic susceptibility to recurrent fevers, generalized severe myalgia, and migratory erythema in an Israeli Arab child with no family history of similar disease. METHODS: DNA sequencing of exons 1-6 of the TNFRSF1A gene (formerly TNFR1) was performed in the patient and his parents to determine the presence of the autosomal-dominant tumor necrosis factor receptor-associated periodic syndrome (TRAPS); informative markers spanning the TNFRSF1A locus were used to genotype all available members of the patient's family. The TNFRSF1A gene was subsequently screened in 69 healthy Arab controls and 96 Caucasian controls. Formal forensic paternity testing was performed on the child. RESULTS: We found a de novo missense mutation in exon 3 of the TNFRSF1A gene, involving a novel C-->T transition encoding a Cys70Arg (C70R) variant, in the Israeli Arab patient. Eight of the common familial Mediterranean fever (FMF) gene MEFV mutations were excluded. This mutation was not present in the parents or siblings, or among the 69 healthy Arab controls. However, another TNFRSF1A variant, Pro46Lys (P46L), was present in 1 of the Arab controls. CONCLUSION: We have identified a TNFRSF1A mutation associated with periodic fever in an Arab patient, and a TNFRSF1A variant, which is variably pathogenic in Caucasians, in an Arab control. This is the first report of a de novo mutation in periodic fevers in general, and also of TRAPS in the Arab population. These findings demonstrate the need to include TRAPS in the differential diagnosis of recurrent fevers in this population.     

Heterozygous Insulin Receptor (INSR) Mutation Associated with Neonatal Hyperinsulinemic Hypoglycaemia and Familial Diabetes Mellitus: Case Series

Mutations in the insulin receptor (INSR) gene are associated with insulin resistance and hyperglycaemia. Various autosomal dominant heterozygous INSR mutations leading to hyperinsulinemic hypoglycaemia (HH) have been described in adults and children (more than 3 years of age) but not in the neonatal period. Family 1: A small for gestational age (SGA) child born to a mother with gestational diabetes presented with persistent hypoglycaemia, was diagnosed with HH and responded well to diazoxide treatment. Diazoxide was gradually weaned and discontinued by 8 months of age. Later, the younger sibling had a similar course of illness. On genetic analysis a heterozygous INSR missense variant p.(Met1180Lys) was found in the siblings, mother and grandfather but not in the father. Family 2: A twin preterm and SGA baby presented with persistent hypoglycaemia, which was confirmed as HH. He responded to diazoxide, which was subsequently discontinued by 10 weeks of life. Genetic analysis revealed a novel heterozygous INSR missense variant p.(Arg1119Gln) in the affected twin and the mother. Family 3: An SGA child presented with diazoxide responsive HH. Diazoxide was gradually weaned and discontinued by 9 weeks of age. Genetic analysis revealed a novel heterozygous INSR p.(Arg1191Gln) variant in the proband and her father. We report, for the first time, an association of INSR mutation with neonatal HH responsive to diazoxide therapy that resolved subsequently. Our case series emphasizes the need for genetic analysis and long-term follow up of these patients.     

The novel missense mutation methionine 442 threonine in the thyroid hormone receptor beta causes thyroid hormone resistance: a case report.

We report a family with thyroid hormone resistance caused by a novel mutation M442T in the thyroid hormone receptor beta (TRbeta) gene. The 59-year-old propositus and one of his two daughters had typical clinical signs of reduced responsiveness of tissues to thyroid hormones. Thus, elevated free T (3) and T (4) plasma concentrations in coexistance with a diffuse nodular goiter, nonsuppressed TSH, and atrial fibrillation with tachycardia were present in the propositus. His affected daughter also had increased levels of free T (3) and T (4) with slightly elevated TSH concentrations. Both affected members harboured a heterozygous M442T TRbeta mutation. The unaffected child had no mutation in the TRbeta gene and no clinical manifestations.     

A novel SCN5A arrhythmia mutation,M1766L,with expression defect rescued by mexiletine

OBJECTIVE: Mutations in the cardiac sodium channel gene, SCN5A, cause congenital long QT syndrome (LQT3), Brugada syndrome, idiopathic ventricular fibrillation, and conduction disease by distinct cellular and clinical electrophysiological phenotypes. METHODS: Postmortem molecular analysis of SCN5A was conducted on an infant who presented shortly after birth with self-terminating torsades de pointes. The infant was treated with lidocaine, propranolol, and mexiletine and was stable for 16 months manifesting only a prolonged QT interval. The infant collapsed suddenly following presumed viral gastroenteritis, was found in 2:1 AV block, and was subsequently declared brain dead. Genomic DNA was subjected to SCN5A mutational analyses and DNA sequencing revealing a novel, spontaneous germline missense mutation, M1766L. The M1766L mutation was engineered into the hH1a clone by site-directed mutagenesis, transfected into embryonic kidney cells (HEK-293), and studied by voltage clamp. RESULTS: The M1766L mutation caused a significant decrease in the sodium channel expression. Co-expression with beta1 subunit, incubation at low temperature, and most effectively incubation with mexiletine partially 'rescued' the defective expression. In addition to this pronounced loss of function, M1766L also showed a 10-fold increase in the persistent late sodium current. CONCLUSIONS: These findings suggest that M1766L-SCN5A channel dysfunction may contribute to the basis of lethal arrhythmias, displays an overlapping electrophysiological phenotype, and represents the first sodium channelopathy rescued by drug.     

Molecular analysis of the MVK and TNFRSF1A genes in patients with a clinical presentation typical of the hyperimmunoglobulinemia D with periodic fever syndrome: a low-penetrance TNFRSF1A variant in a heterozygous MVK carrier possibly influences the phenotype of hyperimmunoglobulinemia D with periodic fever syndrome or vice versa

OBJECTIVE: To describe biochemical findings and the spectrum of mevalonate kinase (MVK) gene mutations as well as an associated TNFRSF1A low-penetrance variant in a series of patients with clinical features of the hyperimmunoglobulinemia D with periodic fever syndrome (HIDS). METHODS: The MVK gene was sequenced in 8 children and 1 adult (including 2 siblings) fulfilling the clinical criteria for HIDS. In addition, sequencing of exons 2, 3, 4, and 6 of the TNFRSF1A gene was performed in patients with only one or no MVK mutation. Mevalonate kinase (MK) enzyme activity in leukocytes and renal excretion of mevalonic acid were also measured. RESULTS: Mutations in the coding region of the MVK gene were detected in 6 patients, and the most common mutation was V377I. Among these patients were 2 novel mutations, both of which were located in exon 6. These novel mutations resulted in the substitution of tryptophan (TGG) by a stop codon (TGA) at amino acid position 188 (W188X) and in the exchange of valine (GTG) for alanine (GCG) at amino acid position 203 (V203A). In 1 patient, a combination of one MVK (V377I) mutation and one TNFRSF1A (R92Q) mutation was present. The patient's clinical phenotype resembled a mixture of variant-type HIDS and tumor necrosis factor receptor-associated periodic syndrome (TRAPS). Her IgD values varied between normal and slightly increased, and the MK activity was in the low-normal range, while urinary mevalonate concentrations were always normal. CONCLUSION: The genotype findings indicate that a relatively small number of genes may be involved in the clinical manifestation of HIDS, with low-penetrance TNFRSF1A variants possibly influencing the HIDS phenotype or MVK mutations contributing to TRAPS.