肝豆状核变性基因类型与临床表型关系研究

目的 了解中国人肝豆状核变性（Wilson‘s disease,WD)患者的P型ATP7B基因突变的分布类型与发生情况,研究WD患者临床表现型和基因型之间的关系。方法 采用生化酶测定,聚合酶链反应,单链构象多态性分析,限制性内切酶图谱和DNA序列分析等分子生物学技术,对57例无亲缘关系家庭的60例WD患者进行ATP7B基因突变的检测。结果 60例中52例有不同程度的肝脏损害症状（87%）,其中30例临床表现为单纯肝脏损害症状,12例为肝脏合并神经系统症状,10例肝脏合并其他症状;7/60例表现为单纯神经系统症状;1例5岁,无临床症状,经DNA序列分析确认基因突变11种,其中错义突变类型5种（R778L,V1140A,G943S,V1106I和V1216M）,碱基缺失1种（1384de117),多态性变化5种（IVS4-5T/C,A2495G,C2310G,IVS18 6C/T和IVS20 5A/G）,WD患者52/114个778位点的精氨酸被置换为亮氨酸（R778L）,R778L基因突变发生率为45.6%,52例WD伴肝脏损害的患者中38例存在R778L基因突变（占73%）,其中14例为R778L纯合型,24例为杂合型。2例V1106I基因突变类型的携带者均为迟发型WD患者(1.7%)。3例已知ATP7B基因突变类型（R778L/V1106I,R778L/V1216M和R778L/R778L）的铜-ATP酶活性较正常对照分别下降44.55%,88.23%和69.49%。结论 1384de117和V1140A为ATP7B新基因突变类型,WD患者的最常见R778L基因突变类型在本组的发生率为45.6%。在临床表现有肝损害的患者中,73%的患者携带R778L基因突变的等位基因。     

Hematologic Phenotype of the Mutations Ivs1-n6 (T →. C), lVS1-n110 (C → A), AND CD39 (C → T) IN CARRIERS OF P-THALASSEMIA IN GREECE

The hematologic phenotype was characterized in heterozygotes for three of the most common β-thalassemia mutations in the Greek population. The study included 17 carriers of β^{+ +} IVSl-n6 (T → C), 21 carriers of β⁺ IVS1-nl10 (G → A), and 17 carriers of β^± CD39 (C → T). The 55 β-thalassemia heterozygotes were selected from among parents of patients on regular transfusion regimns, and the β-thalassemia mutation was identified by means of the polymerase chain reaction to amplify the appropriate regzon of the β-globin gene and then by allele-specific oligonucleotide hybridization. The assessment of hematologic phenotype included complete blood count and quantitation of hemoglobin HbA₂ and HbF and of the globin chain biosynthesis ratio. Comparison and statistical analysis of the hematologic parameters for the three mutations demonstrated no consistent correlation among the three mutations relative to Hb levels, hematocrit, and red cell indices, although heterozygotes for the IVS1-n6 mutation produce red blood cells with slightly higher mean corpuscular volume; significantly lower values of HbA₂ (mean, 3.81% ± 0.62% with four values less than 3.60%) in IVS1-n6 heterozygotes compared with IVS1-n110 heterozygotes (mean, 4.69% ± 0.48%) and CD39 heterozygotes (mean, 4.75% ± 0.50%, P < 0.001); and signafcantly higher HbF levels in CD39 heterozygotes (mean, 2.31% ± 1.52%) compared with IVS1-n6 heterozygotes (mean, 0.79% ± 0.45%, P < 0.01) and IVS1-n110 heterozygotes (mean, 1.17% ± 0.75%, P < 0.01). With respect to the HbA₂ levels, the findings are in agreement with previous studies in Mediterranean populations; the slightly higher levels of HbF in CD39 heterozygotes appear to be reported for the first time.     

26例不典型Rett综合征MECP2基因的突变分析

目的 了解不典型Rett综合征患儿MECP2基因的突变频率、突变类型、是否存在突变热点,寻找基因型和表型的相互关系。方法取26例不典型Rett综合征患儿外周静脉抗凝血,采用Miller’s蛋白酶K氯化钠盐析法提取基因组DNA,采用PCR方法扩增MECP2基因的外显子及结合区,1％的琼脂糖凝胶电泳鉴定目的PCR产物,然后进行DNA直接测序。DNA测序结果与人基因组序列（GeneBank AF030876）比较。结果26例不典型Rett综合征患儿中有12例存在突变。突变类型包括错义突变,由于单个碱基缺失导致的移码突变和剪切位点的突变,其中错义突变为最常见类型。c．397C〉T为3例,c．473C〉T、c．916C〉T、c．806delG各为2例,c．397A〉G、c．1005G〉A、c．IVS2-2A〉T各为1例。结论不典型Rett综合征患儿存在MECP2基因突变,R133C、T158M和R306C为其热点突变。基因突变类型和表型之间有一定的相关性。     

Glycogen storage disease type I: diagnosis and phenotype/genotype correlation

Glycogen storage disease type Ia (GSD Ia) is caused by mutations in theG6PC gene encoding the phosphatase of the microsomal glucose-6-phosphatase system. GSD Ia is characterized by hepatomegaly, hypoglycemia, lactic acidemia, hyperuricemia, hyperlipidemia and short stature. Other forms of GSD I (GSD I non-a) are characterized by the additional symptom of frequent infections caused by neutropenia and neutrophil dysfunction. GSD I non-a is caused by mutations in a gene encoding glucose-6-phosphatase translocase (G6PT1). We report on the molecular genetic analyses of G6PC and G6PT 1 in 130 GSD Ia patients and 15 GSD I non-a patients, respectively, and provide an overview of the current literature pertaining to the molecular genetics of GSD I. Among the GSD Ia patients, 34 different mutations were identified, two of which have not been described before (A65P; F117C). Seventeen different mutations were detected in the GSD I non-a patients. True common mutations were identified neither in GSD Ia nor in GSD I non-a patients,Conclusion: Glycogen storage disease type Ia and and type I non-a are genetically heterogenous disorders. For the diagnosis of the various forms of glycogen storage disease type I, molecular genetic analyses are reliable and convenient alternatives to the enzyme assays in liver biopsy specimens. Some genotype-phenotype correlations exist, for example, homozygosity for oneG6PC mutation, G188R, seems to be associated with a glycogen storage disease type I non-a phenotype and homozygosity for the 727G>T mutation may be associated with a milder phenotype but an increased risk for hepatocellular carcinoma. Published online: 27 July 2002     

四氢生物蝶呤反应性苯丙氨酸羟化酶缺乏症的临床与基因研究

目的 探讨四氢生物蝶呤（tetrahydrobiopterin,BH4）反应性苯丙氨酸羟化酶（phenylalanine hydroxylase,PAH）缺乏症临床表型和基因型的关系。方法 38例高苯丙氨酸血症（hyperphenylalaninemia,HPA）患儿均进行口服BH。负荷试验（20ms／kg）或Phe-BH。联合负荷试验,同时进行尿蝶呤谱分析、红细胞二氢蝶啶还原酶（dihyaropteridine reductase,DHPR）测定。对7例BH4反应性PAH缺乏症患儿采用聚合酶链反应（PCR）和单链构象多态性（single strand conformation polymorphism,SSCP）分析对PAH外显子进行突变筛检,并结合DNA直接测序方法进行突变分析。结果 确诊10例BH4反应性PAH缺乏症患儿,男6例,女4例;平均年龄7．8个月;生化代谢表型均为轻度或中度HPA。7例BH4反应性PAH缺乏症患儿PAH基因型分别为S70del／-、R241C／R243Q、S70del／A389G、Y166X／-、R11lX/-、EX6-96A〉G／R241C和IVS4-1G〉A／R241C。A389G是新发现的突变基因型。结论 BH4反应性PAH缺乏症多表现为轻、中度HPA生化代谢表型,R241C是BH4反应性相关突变基因型中较常见的一种类型。推测S70del可能是一种BH4反应性相关突变类型.     

伴皮层下囊肿的巨脑性白质脑病一家系MLC1基因突变分析

收集伴皮层下囊肿的巨脑性白质脑病(MLC)先证者及其父母的临床资料,采用聚合酶链反应和DNA 直接测序法进行MLC1 基因突变检测。患儿临床表现为运动发育迟缓、巨颅,头颅MRI 扫描显示弥漫性脑白质肿胀,伴双侧额顶部皮层下囊肿。基因测序结果发现患儿携带MLC1 基因2 个杂合突变:第3 外显子的错义突变c.217G>A(p.Gly73Arg)和第9 内含子的剪接位点突变c.772-1G>C in IVS9-1。患儿的父母均为c.772-1G>C in IVS9-1 杂合突变携带者,无临床症状。可推测患儿c.772-1G>C in IVS9-1 突变来源于父母;c.217G>A(p.Gly73Arg)为新生突变,为国内外首次报道。     

以小分子蛋白尿为主要表现的Dent病六例临床及基因分析

目的 分析和总结6例儿童Dent病的临床及基因特征.方法 总结6例Dent患儿的临床资料,采用聚合酶链反应及直接测序的方法检测CLCN5基因.结果 6例患儿均有不同程度的小分子量蛋白尿和高钙尿症.其中3/6有血尿,4/6有肾钙化,3/6有低磷血症,1/6有佝偻病.在这6个家系中发现了6个CLCN5基因突变,包括3个无义突变、1个剪切位点突变、2个错义突变,分别为L594fsX595、R637X、R467X、IVS4-2A>G、S244L和V505G.其中,IVS4-2A>G和V505G是新突变.结论 小分子蛋白尿和高钙尿症是6例Dent病患儿的主要临床特征;Dent病可有Bartter综合征样表现,需要基因诊断进一步确诊.     

7例原发性免疫缺陷病的临床及基因突变分析

探讨原发性免疫缺陷病的临床特点及其致病基因突变特点。7例患儿均为男性,年龄5个月至4岁6个月,均有反复呼吸道感染、肺炎病史,免疫球蛋白IgG及IgM水平低下,淋巴细胞亚群的绝对值或比例异常。高通量测序发现病例1的BTK基因存在c.1684C > T突变,病例2的BTK基因存在IVS8+2T > C剪接位点突变,两个突变均遗传自患儿母亲。病例3~5存在IL2RG基因突变,分别为c.298C > T、IVS3-2A > G以及c.164T > A突变,其中c.164T > A突变未见报道。病例6的RAG2基因存在c.204C > G突变,病例7的RAG2基因存在c.913C > T以及c.824G > A复杂杂合突变,分别遗传自父母。原发性免疫缺陷病患者存在免疫学指标异常,高通量测序有助于确诊。     

Molecular correlations in phenylketonuria: mutation patterns and corresponding biochemical and clinical phenotypes in a heterogeneous California population.

We studied 133 California phenylketonuria (PKU) patients and one obligate heterozygote to delineate the molecular basis of PKU in a population with greater ethnic diversity than in previous studies, and to determine whether a correlation exists between genotype and clinical phenotype, with the latter defined by both the diagnostic pretreatment blood phenylalanine (PHE) level and cognitive (IQ) test scores. To determine PAH genotypes, we used PCR-mediated amplification, denaturing gradient gel electrophoresis, and direct sequencing on dried whole blood samples. Where possible, mutation severity was defined according to predicted in vitro PAH enzyme activity estimated by using Cos cell expression analysis for a given mutation. We then asked whether mutation severity, as defined by such expression analysis, correlated with pretreatment PHE levels or with IQ test results. A mutation was identified in 236 (88%) of 267 mutant alleles. Seventeen new mutant alleles were found; A47E, T81P, I102T, E182G, T328D, Y343P, K371R, Y387H, A389E, E422K, IVS9nt5, IVS11nt20, delS70, del364-368/del198-220, delF299, delT323, and -1C/T. In striking contrast to a number of studies in other populations, in this study, based on predicted PAH activity, we observed no correlation between mutation severity and pretreatment PHE levels. There was also no correlation between genotype and IQ. We conclude that in samples collected from an ethnically heterogeneous population, there is no correlation of mutation severity with either pretreatment PHE levels or IQ measurement in treated patients. We caution that genetic counseling in PKU should incorporate the notion that prognosis may not be predicted with precision based on mutation analysis in a given patient.     

Leigh syndrome due to compound heterozygosity of dihydrolipoamide dehydrogenase gene mutations. Description of the first E3 splice site mutation

A boy with recurrent episodes of hypoglycaemia and ataxia, microcephaly, mental retardation, permanent lactic acidaemia, intermittent 2-oxoglutaric aciduria as well as elevation of serum branched chain amino acids was diagnosed with dihydrolipoamide dehydrogenase (E3) deficiency. Analysis of genomic DNA revealed compound heterozygosity for two novel mutations: I393T in exon 11, located at the interface domain of the protein and possibly interfering with its dimerisation, and IVS9+1G>A located at a consensus splice site. A heterozygous polymorphism was also detected. In the patient's cDNA the I393T mutation and the polymorphism appeared to be homozygous, indicating that the mRNA coming from the IVS9+1G>A mutant allele is not stable. CONCLUSION: as opposed to the non-neurological phenotype of patients with a homozygous G229C mutation, this patient developed Leigh syndrome. Dihydrolipoamide dehydrogenase and pyruvate dehydrogenase complex activities in muscle were 29% and 14% of the lowest control values, respectively. Pyruvate dehydrogenase complex activity in fibroblasts was normal, however, indicating that the biochemical examination of defects in energy metabolism should be performed in a more energy demanding tissue.     

A novel <Emphasis Type="BoldItalic">WT1</Emphasis> gene mutation in a patient with Wilms’ tumor and 46, XY gonadal dysgenesis

Denys–Drash syndrome (DDS) is a rare genetic disorder featuring the triad of Wilms' tumor, early-onset renal failure, and 46, XY disorder of sex development. DDS is usually caused by heterozygous missense mutations in the zinc-finger region of the WT1 gene. The most frequent constitutional WT1 mutations in DDS patients are missense mutations in exons 8 and 9. We present a new case of variable DDS in a child who was found to have a novel heterozygous missense mutation in exon 7 (c.905G>T) and a splicing mutation in exon 6 (IVS6-1G>T).     

Truncation and microdeletion of EVC/EVC2 with missense mutation of EFCAB7 in Ellis‐van Creveld syndrome

Ellis‐van Creveld syndrome (EvC) is a ciliopathy with cardiac anomalies, disproportionate short stature, polydactyly, dystrophic nails and oral defects. To obtain further insight into the genetics of EvC, we screened EVC/EVC2 mutations in eight Vietnamese EvC patients. All the patients had a congenital heart defect with atypical oral and/or skeletal abnormalities. One had compound heterozygous EVC2 mutations: a novel mutation c.769G > T‐p.E177X in exon 6 inherited from father and another previously reported c.2476C > T‐p.R826X mutation in exon 14 inherited from mother. The EVC2 mRNA expression level was significantly lower in the patient and her parents compared to controls. Another case had a novel heterozygous EVC mutation (c.1717C > G‐p.S572X) in exon 12, inherited from his father. Of note, the mother without any EVC mutation on Sanger sequencing showed a lower expression level of EVC mRNA compared with controls. SNP array analysis revealed that the patient and mother had a heterozygous 16.4 kb deletion in EVC. This patient also had a heterozygous novel variant in exon 9 of EFCAB7 (c.1171 T > C‐p.Y391H), inherited from his father. The atypical cardiac phenotype of this patient and the father suggested that EFCAB7 may modify the phenotype by interacting with EVC. In conclusion, we detected two novel nonsense mutations and a partial deletion of EVC/EVC2 in two Vietnamese families with EvC. Moreover, we found in one family a missense mutation of EFCAB7, a possible modifier gene in EvC and its related disorders.     

苯丙酮尿症患儿苯丙氨酸羟化酶基因突变的研究

目的了解宁夏地区苯丙酮尿症(PKU)儿童苯丙氨酸羟化酶(PAH)基因突变的特征。方法以经新生儿疾病筛查及气相色谱-质谱联用技术确诊的30例宁夏PKU儿童为病例组,30例正常儿童为对照组,应用PCR技术扩增PAH基因的3、5、6、7、11和12,六个外显子,再经单链构象多态性分析和DNA测序分析PCR扩增产物。结果在60个等位基因中检出51个突变基因,检出率85%;六个外显子共检出16种致病突变,包括8种错义突变(R241C、R243Q、R252Q、G 257 V、R359K*、R408Q、R 413 P、Q419R),3种剪接突变(IVS 4-1 GA、Y 204 C、IVS 7+2 TA),3种无义突变(R 111 X、Q160X、Y356X),1种同义突变(V399V)和1种缺失突变(N183del);R243Q突变频率最高,检出率为18.3%,其次是Y 204 C(11.7%)、IVS 4-1 GA(10.0%)、R 111 X(6.7%)和IVS 7+2 TA(6.7%)。病例组中发现Exon 6的N183del(C.547-549del GAA)缺失突变和Exon 11的R359K(C.1078GA)错义突变,为国内首次发现;病例组和对照组中均检出V245V(C.735GA)和Q232Q(C.696AG)两种静止突变,且差异无统计学意义(P0.05)。结论宁夏PKU儿童PAH基因六个外显子最常见的突变类型是错义突变,特别是R243Q;发现中国人群PAH基因的2种新的突变。     

Early T‐Cell Precursor Acute Lymphoblastic Leukemia in an Infant With an NRAS Q61R Mutation and Clinical Features of Juvenile Myelomonocytic Leukemia

Early T‐cell precursor acute lymphoblastic leukemia (ETP‐ALL) is a subtype of T‐acute lymphoblastic leukemia (T‐ALL) arising from a primitive precursor. We present a unique case of an infant with ETP‐ALL with a missense NRAS mutation in codon 61 (c.182A>G, p.Q61R). The patient also had a minor population of non‐ETP T‐ALL blasts and clinical features typically associated with juvenile myelomonocytic leukemia (JMML), namely, absolute monocytosis, splenomegaly, and elevated hemoglobin F. The treatment was initiated with chemotherapy, followed by cord blood transplantation. The patient achieved remission, but unfortunately died from transplant‐related complications. This case highlights an NRAS mutation in ETP‐ALL with JMML‐like phenotype.     

combination of IVS2.849 A-G witH IVS1.1 G-A: a mutation of beta-globin gene in a Turkish beta-thalessemia major patient

Beta-thalassemia, which is an autosomal recessive disease, is among the most common hemoglobinopathies in Antalya, Turkey. Mutations found in Turkish β-thalassemia patients constitute a heterogeneous group, which is mostly composed of point mutations and, only in very rare cases, a deletion or an insertion causes affected or carrier phenotypes. Reverse dot blot hybridization (RDBH) method is used for screening common mutations, and sequence analysis and silver staining were performed consecutively to detect any uncommon mutation. The authors report a first Turkish family with a rare variant—intervening sequence 2 (IVS2) 849 (A-G). The proband's mother and father were determined as carriers of IVS2.849 (A-G) and IVS1.1 (G-A) mutations, respectively. Proband is the first child of the family and she has an IVS2.849 (A-G)/IVS1.1 (G-A) genotype with β-thalassemia major phenotype. Prenatal diagnosis was performed for the second child, and genotype of the fetus was determined as IVS2.849 (A-G)/Normal. This first report of IVS2.849 (A-G) mutation in Turkish population shows that there are many more mutations contributing the heterogeneity of the mutation spectrum of β-globin gene in the Turkish population, which indicates migrations of different ethnic origins.     

Aromatic l-amino acid decarboxylase deficiency in Taiwan

BackgroundAromatic l-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive disorder of neurotransmitter synthesis. It has unique clinical presentations.AimsThe purpose of this study is to delineate the clinical features and molecular spectrum of AADC deficiency in Taiwanese infants and children.MethodsWe report eight patients with characteristic clinical manifestations of AADC deficiency. Clinical presentations, treatment response, outcome and mutations of DOPA decarboxylase (DDC) gene were analyzed.ResultsThe clinical manifestations were similar to those previously reported, including symptoms onset before age 1 year with features of severe floppiness, oculogyric crises, athetoid movement, prominent startle response, tongue thrusting, ptosis, paroxysmal diaphoresis, nasal congestion, diarrhea, irritability and sleep disorders. In addition, we observed that all patients (100.0%) had small hands and feet. During the period of follow-up, all of them (100.0%) presented severe floppiness in spite of therapeutic trials with vitamin B6, dopamine agonist, MAO inhibitor and/or anticholinergics. Three different mutations were identified in the DDC gene, including two novel mutations 1303 C > T and 1367ins A and one IVS 6 + 4 A > T mutation. The IVS 6 + 4 A > T was a splicing mutation, which inserted an additional 37 nt of intron 6 into the DDC mRNA. Thirteen out of 16 alleles (81.3%) carried IVS 6 + 4 A > T mutation and the IVS 6 + 4 A > T alleles shared a conserved haplotype.ConclusionsPatients with AADC deficiency in Taiwan have particular clinical manifestations of small hands and feet, which have rarely been mentioned in the literature. The prevalence of IVS 6 + 4 A > T splicing mutation is high in our study group and the IVS 6 + 4 A > T mutation might have a founder effect.     

Berardinelli-Seip congenital lipodystrophy

Berardinelli-Seip congenital lipodystrophy (BSCL) is a very rare genetic disorder characterized by lipoatrophy, hypertriglyceridemia, hepatomegaly and acromegaloid features. On the basis of mutational and haplotype analysis, BSCL families have been classified into three types BSCL 1, BSCL2 and BSCLX. We report Berardinelli-Seip congenital lipodystrophy (BSCL2 type) in three subjects from two unrelated Indian families (family1 and family2). The mutation (c.IVS2 11 A GT G ) found in affected members of family1 is a newly identified mutation. We also report the association of renal anomaly with this new mutation.     

Citrin 缺陷导致的新生儿肝内胆汁淤积症 SLC25A13 基因分析

目的：Citrin 缺陷导致的新生儿肝内胆汁淤积症（NICCD）是一种由SLC25A13基因突变引起的常染色体隐性遗传病,临床可表现为肝内胆汁淤积性黄疸、低出生体重、生长迟缓和低蛋白血症等。本研究通过DNA测序技术探讨中国NICCD患儿 SLC25A13 基因突变类型。方法：针对 SLC25A13 基因的 18 个外显子及其侧翼区碱基序列设计引物,应用 PCR 技术扩增目的片度。PCR 扩增、纯化后直接测序,确定其突变类型。IVS16ins3kb 突变则采用巢式 PCR 和 RT-PCR 进行检测。结果：发现7种SLC25A13基因突变类型,包括851del4、1638ins23、IVS16ins3kb、IVS6+5G>A、c.775C>T（p.Q259X)、c.1505C>T（p.P502L） 和 c.1311C>T（p.C437C）;并确认一种复合突变类型［1638ins23+IVS16ins3kb］。其中c.775C>T（p.Q259X）、c.1505C>T（p.P502L）和 c.1311C>T（p.C437C）为新发现的基因突变类型。在20例NICCD患儿中,6 例为 851del4 纯合突变,7 例为杂合突变,另有 7 例为单一突变类型的杂合子。突变类型以 851del4 为主,占所有突变类型64%;其次为 1638ins23、IVS16ins3kb 和 IVS6+5G>A（分别占15%、12% 和 6%）。结论：851del4突变在 NICCD 患儿中最为常见。