Fabry病家系的α-半乳糖苷酶A基因突变研究

目的 通过检测3个Fabry病家系基因突变类型明确基因诊断,并进行家系成员的基因型检测.方法 通过PCR和直接测序的方法,对3个Fabry家系的先证者及部分家系成员外周血DNA进行α-半乳糖苷酶A编码GLA基因7个外显子及其相邻内含子的DNA序列检测.结果 （1）先证者1的GLA基因7号外显子内1142位点发生碱基缺失（1142delG）,1142位碱基G的缺失导致蛋白质翻译在390位氨基酸提前终止,该突变国内外均未见报道;（2）先证者2的GLA基因6号外显子内902位点存在1个错义突变,碱基G被A取代,导致其编码的第301位氨基酸由精氨酸变为谷氨酰胺（902G＞A,R301Q）;（3）先证者3的GLA基因3号外显子内484位点存在1个错义突变,碱基T被C取代,导致其编码的第142位氨基酸由半胱氨酸变为精氨酸（484T＞C,C142R）.在3个家系的部分成员中进行基因检测,检出GLA突变基因携带者共6例,其中男性半合子1例,女性杂合子5例,突变类型均与相应先证者符合.100条正常X染色体对照中均未发现上述位点异常.结论 本研究在3个Fabry病家系中检出3种GLA基因突变,其中1142delG为新发现的突变,并在3个家系的部分家系成员中检出男性半合子1例,女性杂合子5例.     

一个Fabry病家系的基因突变和临床表型研究

目的对一个临床表现以肾脏损害为主的Fabry病家系进行调查,分析其基因突变和临床特点。探讨不同突变类型对临床表型的影响。方法收集该例先证者及其家族成员的临床资料。采集先证者及其姐姐和一名健康对照者的外周血,应用荧光底物法检测a半乳糖苷酶A（toga[A）的酶活性;提取血液基因组DNA,PCR分段扩增α—galA基因的7个外显子,产物纯化后进行DNA测序,检测是否存在突变位点。结果①临床调查患者家系发现5名男性患者,均发展至终末期肾脏疾病（endstage renaldisease,ESRD）,伴有肢端疼痛、皮肤血管胶质瘤及少汗等Fabry病典型表现;3名女性杂合子,临床表现各异;②regalA活性检测示先证者酶活性明显下降,其姐姐α-galA活性在正常范围;③基因检测发现先证者regalA基因第2外显子的第112个密码子上的碱基胞嘧啶（c）被胸腺嘧啶（T）替代,因此导致由原本翻译的精氨酸变成了半胱氨酸（p．R112C）,形成错义突变,从而导致α-galA酶活性的降低或缺乏。结论发现了一个新的Fabry病家系,并明确了该家系的基因突变特点。在此家族中,我们发现除了外胚层组织损害,α—galA基因错义突变p．R112C亦可导致中胚层组织（如肾脏）的严重损害。     

一例女性Fabry病并发薄基底膜肾病及其家系调查

目的 了解具有两种遗传性疾病,即Fabry病并发薄基底膜肾病（TBMN）的临床病理和基因突变特点以及家系患病情况。 方法 总结分析本院收治的1例41岁女性Fabry病并发TBMN患者的临床病理特征和基因突变情况,同时对家系成员进行调查及相关检测。 结果 先证者呈现典型的Fabry病的肾外临床表现,包括皮疹、神经痛、眩晕、耳鸣、肥厚型心肌病等,同时亦有蛋白尿、镜下血尿及高血压等肾脏受累表现;肾活检光镜下病理改变为局灶性节段性肾小球硬化（FSGS）,部分足细胞空泡变性;电镜下肾小球脏层上皮细胞胞质内多数髓磷脂小体形成,肾小球基底膜（GBM）弥漫性变薄,厚度为（216±31） nm。家系调查及基因突变检测显示先证者女儿除有典型Fabry病肾外表现外,亦有以血尿为主的肾脏症状。先证者的1个妹妹仅表现为镜下血尿。先证者及其女儿α-半乳糖苷酶 A（α-Gal A）活性分别为33和75活性单位（正常参考值为100~500活性单位）,且2人均携带新发现的GLA基因突变——1208ins21 bp及COL4A3基因多态性——c:3627 G>A（p:M1209I）。仅表现为镜下血尿的先证者的妹妹仅携带COL4A3基因的c:3627 G>A（p:M1209I）多态性,α-Gal A活性正常,无GLA基因突变。 结论 对于Fabry肾病患者呈现血尿,尤其是表现为家族性血尿时,应考虑并认真排除并发TBMN的可能。     

14例Fabry病肾损害的临床、病理及基因突变特点的分析

目的 探讨Fabry病肾损害的临床病理及α-半乳糖苷酶A(α-Gal A)基因(GLA 基因)突变的特点.方法 回顾性分析14例Fabry病患者的临床、肾脏病理及GLA基因突变等特点.结果 Fabry病肾损害在肾活检患者中检出率为0.074％,平均确诊年龄(30.57±9.32)岁,男∶女=2.5∶1.尿蛋白量中位数为1.71 g/24 h[(0.32～ 4.71)g/24 h].5例有血尿,4例有肾功能受损,肾外受累的表现以血管角质瘤最多见(10/14),其次为心脏病变(6/14).经典型患者9例,迟发型5例,其中6例有肾脏病家族史.肾脏病理光镜下可见明显的肾小球细胞空泡变性,部分患者可见硬化的肾小球.电镜下2例女性患者为部分足细胞内有髓磷脂样小体形成,其余病例所有足细胞内均可见髓磷脂样小体.4例测定α-Gal A活性的先证者均低于正常值.12例先证者进行了GLA基因突变分析,11例发现有GLA基因突变.3个新突变为碱基插入或缺失突变,临床表型均为经典型Fabry病.大多数迟发型患者携带的基因突变位于酶结构的包埋区或部分包埋区(3/11).在已证实的GLA基因突变中,携带I91T、R112H、Q312H的先证者主要表现为“迟发型”;携带W162X、F169S、S201F、N272K及L310R的先证者均表现为“经典型”.结论 本组Fabry病肾损害患者占肾活检的0.074％,常伴有血管角质瘤及心脏受累,且不同的GLA基因突变可能与患者的表型密切相关.     

成人经典型Bartter综合征家系CLCNKB基因突变的研究

目的 分析1个成人经典型Bartter综合征家系CLCNKB基因突变特点。 方法 用PCR方法对先证者CLCNKB基因19个外显子及侧翼序列进行扩增,PCR产物纯化后直接测序或构建T-A克隆测序检测其基因变异。 结果 先证者CLCNKB基因表现为G433E和cDNA 753delG复合杂合突变。家系分析表明,杂合错义突变G433E来自父亲,杂合缺失突变cDNA 753delG来自母亲。患者弟弟携G433E,其妹妹正常。正常对照100条染色体中未发现同样变异。 结论 在1个成人迟发经典型Bartter综合征家系中发现了CLCNKB基因2个突变位点,经检索文献及人类基因突变库（HGMD）,cDNA 753delG为新发现突变位点。     

经典型Bartter综合征家系CLCNKB基因突变分析

目的 研究一个经典型Bartter综合征家系CLCNKB基因突变情况。 方法 提取该家系各成员患者外周血淋巴细胞基因组DNA,应用PCR扩增CLCNKB基因全部外显子及侧翼序列,并直接测序检测突变。选取50例无亲缘关系的健康人作为对照。 结果 在患者中检测到1个杂合（错义）突变,其第4号外显子,第482位碱基T→G突变,造成第161位氨基酸由亮氨酸变为精氨酸（482T>G,L161R）;家系中母亲为杂合突变（L161R杂合突变）,父亲未发现突变;查阅国内外文献及人类基因突变数据库,L161R未见报道,属新发现的突变。 结论 发现了一种新的CLCNKB基因突变：L161R。     

中国汉族人3个家族性激素耐药型肾病综合征家系WT1和PLCE1基因突变分析

目的 分析中国汉族人家族性激素耐药型肾病综合征（SRNS）家系WT1和PLCE1基因突变及其特点。 方法 研究对象为A、B、C 3个汉族人SRNS家系的先证者（已除外NPHS2基因突变）及其父母,A、B 2个家系先证者的姐姐,50例尿检正常的汉族成年人作为对照人群。取所有研究对象外周静脉血3 ml,提取基因组DNA,PCR扩增WT1基因全部10个外显子和PLCE1基因全部31个编码外显子及其周围的部分内含子,应用直接DNA序列测定法和限制性片段长度多态性PCR（RFLP-PCR）分析法检测WT1和PLCE1基因变异。 结果 未发现WT1和PLCE1基因的致病突变。但是,在3个SRNS家系的先证者检测到3个WT1基因多态性：126C>T（P42P）、IVS5－64A>G和903A>G（R300R）,其中IVS5－64A>G为新发现的WT1基因多态性,126C>T和903A>G已见文献报道;还检测到13个PLCE1基因多态性 －134A>G、810T>C（C270C）、960G>A（E320E）、IVS11－28C>G、IVS15+26A>C、4724G>C（R1575P）、IVS20+40C>T、IVS21+64G>A、IVS22－26T>A、5320C>T（T1777I）、5780A>G（H1927R）、IVS27+24A>G和IVS31+48_49insT,其中IVS22－26T>A为新发现的PLCE1基因多态性,其余12个PLCE1基因多态性已见公布。 结论 WT1和PLCE1基因突变不是本研究3个中国汉族人家族性SRNS家系的主要致病原因。     

中国Alport综合征一家系的基因突变检测与临床表型分析

目的:应用高通量测序技术,检测一个中国遗传性肾病家系的致病基因突变,探讨靶区域捕获和高通量测序方法在遗传性肾病基因筛查中的可行性。方法:收集家系临床资料和外周血样本;分析先证者的临床资料,并观察肾穿组织病理,采用目标区域捕获和高通量测序技术,对先证者355个遗传性肾病相关基因的外显子进行突变筛查;应用Sanger测序,在其他家庭成员中进行突变位点验证及突变-表型共分离分析,并对突变位点进行多物种的保守性分析。结果:结合临床检验结果和肾活检病理观察,先证者符合慢性肾小球肾炎,不排除Alport综合征的可能。基因筛查发现,该家系可确诊为X染色体显性遗传Alport综合征,家系中所有女性患者均为X染色体COL4A5基因c.3641GA(p.Gly1214Glu)杂合突变,而男性患者均为该位点的半合子。且该位点在多个物种中具有高度的序列保守性。结论:该遗传性肾病家系是X染色体显性遗传Alport综合征,致病突变位点为COL4A5 c.3641GA(p.Gly1214Glu)。靶区域捕获和高通量测序技术成本低、高通量、准确性高,适用于遗传性肾病家系的基因突变筛查。     

VHL基因N131Y突变导致家族性胰腺多发囊肿

目的探讨1个单纯表现胰腺多发囊肿的Von Hippel-Lindau(VHL)综合征家系的VHL基因变异情况。方法调查1个VHL病家系临床资料,绘制树状图;抽取该家系3位成员外周血,提取基因组DNA,应用聚合酶链式反应(PCR)以及实时定量PCR对VHL基因进行点突变以及基因缺失进行筛查。结果该家系中仅先证者和其母亲表现为胰腺多发囊肿,且基因检测结果显示先证者和其母亲均存在VHL基因编码区第391位核苷酸A突变为T,导致第131号编码氨基酸由天冬酰胺变成了酪氨酸,为VHL基因未曾报道过的突变位点;而其父亲均无异常表现。结论 VHL综合征中,VHL基因2号外显子发生该位点突变,则仅表现为胰腺多发囊肿;对于单纯表现为胰腺多发囊肿的患者,尤其是青年或无胰腺疾病家族史者需考虑VHL综合征的可能。     

慢性HBV感染者TNFα-308位点多态性与HBV C基因区突变的关系

目的 研究慢性乙型肝炎病毒（HBV）感染者肿瘤坏死因子α（TNFα）-308位点的基因多态性与HBV C基因区突变的关系.方法 对95例慢性HBV感染者进行研究,采用聚合酶链反应.限制性片断长度多态性（PCR-RFLP）技术分析患者TNFα-308位点的多态性.对PCR产物直接测序,检测HBV C基因区nt1762/1764、nt1896、nt1899、nt1862、aa60、as87及aa97位点是否存在突变.采用Fisher＇s精确概率法比较TNFα-308位点不同基因型患者HBV C基因区常见突变的检出率.结果 TNFα-308位点共发现3种多态性,分别为G/G型63例（63/95,66.3%）,G/A型28例（28/95,29.5%）,A/A型4例（4/95,4.2%）.TNFα-308位点G/G、G/A、A/A基因型患者HBV C基因区aa87位点及as97位点突变型检出率均分别为39.3%（24/61）、11.5%（3/26）和50.0%（2/4）,差异有统计学意义（F=7.658,P〈0.05）;而nt1762/1764、nt1896、nt1899、nt1862以及aa60位点突变型检出率比较差异无统计学意义（F值分别为0.669、1.542、1.123、2.420和0.966,P值均〉0.05）.结论 慢性HBV感染者TNFα-308位点G/A基因型相对于G/G基因型不易发生HBV抗原性变异,有利于HBV的清除.     

A novel GLA mutation in a Fabry family with glucose-6-phosphate dehydrogenase deficiency

Fabry disease is an X-linked lysosomal disease caused by mutations of the alpha-galactosidase A (GLA) gene at chromosome subband Xq22.1. To date, more than 600 genetic mutations have been identified to determine the nature and frequency of the molecular lesions causing the classical and milder variant phenotypes and for precise carrier detection. We report here a Fabry family (mother, son and daughter) where the alpha-galactosidase A defect was associated with a glucose-6-phosphate dehydrogenase (G6PD) deficiency. Mutation analysis revealed for the GLA gene the presence of a new mutation, i.e., a small deletion (c.452delA) on exon 3 and for the G6PD gene the presence of 2 mutations, p.V68M (G6PD Asahi, G6PD A+) and p.N126D (G6PD A+) on exon 3 and exon 4, respectively.     

Anderson–Fabry disease: a case-finding study among male kidney transplant recipients in Austria

The diagnosis of Anderson–Fabry disease is often delayed or even missed. As severe renal manifestations are a hallmark of alfa-galactosidase A (AGAL) deficiency, we tested the hypothesis that Anderson–Fabry disease is under-recognized among male kidney transplant recipients. This nation-wide study in Austria enrolled 1306 patients (ca 65% of all kidney transplanted males) from 30 kidney centers. AGAL activity was determined from filter paper dried blood spots by a fluorescence assay. A positive screening test was defined by an AGAL activity below 1.5 nmol/h/ml. In patients with a positive blood spot-screening test, AGAL activity was re-examined in peripheral blood leukocytes. Genetic testing for mutations in the GLA gene was performed by sequencing to confirm the diagnosis of Anderson–Fabry disease. Two previously not recognized cases with Anderson–Fabry disease were identified. Our study is the first showing that a diagnosis of Anderson–Fabry disease can be missed even in patients who undergo kidney transplantation. Case-finding strategies may be considered a useful tool for diagnosis of this rare disease that may be somewhat more prevalent among kidney transplant recipients compared with dialysis populations.     

Non-invasive high-risk screening for Fabry disease hemizygotes and heterozygotes

The most appropriate time for screening for Fabry disease (FD) is school age. For this reason, we developed non-invasive methods for measuring urinary alpha-galactosidase A (alpha-gal A) protein, using enzyme-linked immunosorbent assay (ELISA), and for globotriaosylceramide (GL-3), using tandem mass spectrometry (MS/MS). We measured these two biomarkers in the urine of previously diagnosed FD hemizygotes and heterozygotes, and in controls. All the classic FD hemizygotes were clearly distinguished from controls by either method alone, and combining the two assays produced 96% sensitivity for detecting heterozygotes. To assess the utility of these methods for screening school children and adults at high risk of FD, a pilot study was conducted. To distinguish FD from 432 controls, cut-off values for alpha-gal A protein and GL-3 were set at the 5th and 95th centile values of the controls, respectively. Among the high-risk patients, the measurements exceeded the cut-off values for both biomarkers in male and female subjects and were strong indicators for Fabry hemizygotes and heterozygotes. However, we recommend that if the results of the first measurements exceed the cut-off values for only one of these biomarkers, another urine sample should be requested for re-assay to confirm the result.     

Mutational analysis and functional correlation with phenotype in German patients with childhood-type hypophosphatasia.

The tissue-nonspecific alkaline phosphatase (TNSALP) gene from five German family members with childhood-type hypophosphatasia (HOPS) was analyzed using the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP)-direct sequencing method. Four novel missense mutations (T51M, R54S, L258P, and R374H) and two that had been described previously (A160T and R206W) were detected in the respective patients. Mutation A160T was detected in 3 distinct patients, and a polymorphism V505A that had been described previously was detected in the same allele as L258P mutation in 1 patient and in 2 fathers whose V505A alleles were not transmitted to the probands. No other mutations were found in 2 patients. Transient expression of the mutant proteins in COS-1 cells showed that the four novel mutations and R206W were severe alleles, whereas A160T was a moderate allele. Analysis of its enzymatic activity and genetic transmission patterns confirmed that V505A was a polymorphism. Immunoprecipitation of the transiently expressed proteins showed that levels of the 80-kDa mature form of the enzyme were diminished or absent with the severe alleles; instead, levels of high-molecular mass disulfide-linked aggregates were increased. These results suggest that in compound heterozygotes, the combination of severe and moderate alleles may combine to cause the mild phenotype seen in childhood-type HOPS.     

Mutation analysis of SLC12A1 gene in nine Chinese patients with Bartter syndrome type I

Objective To analyze the mutations of SLC12A1 gene in nine Chinese families with Bartter syndrome type I (BS1), and analyze the relationship between genotype and phenotype. Methods The next generation sequencing was used to detect mutations in nine BS1 patients including eight with antenatal BS (aBS) and one with classical BS (cBS). Clinical characteristics and biochemical findings at the first admission as well as follow-up were reviewed. Results 15 different mutations of SLC12A1 gene were identified, including 11 novel ones. Among nine probands, seven were compound heterozygotes, two were homozygotes. All patients presented with polydipsia and polyuria, and eight with growth retardation. All patients had lower than-normal serum chloride concentration, metabolic alkalosis, and elevated basal renin activity and aldosterone, and seven had hypokalemia. Through treatment of indomethacin and/or potassium chloride, biochemical indicators could roughly restored normal. Conclusion These findings will enrich the human gene mutation database (HGMD) and provide valuable references to the genetic counseling and diagnosis for Chinese population.     

A novel small insertion mutation, C.1030_1031ins (T) in α-galactosidase A leads to renal variant fabry disease

Fabry disease is a rare X-linked recessive glycosphingolipid storage disease that is caused by a deficiency of the lysosomal α-galactosidase A (GLA) enzyme, encoded by the GLA gene. This deficiency leads to the accumulation of glycosphingolipids throughout the body, which, in turn, causes multisystem diseases associated with renal, cardiovascular, and cerebrovascular complications. Recent molecular studies of GLA have demonstrated the existence of atypical variants in Fabry disease, suggesting significant genotype-phenotype correlations. In this study, we describe a renal variant of Fabry disease caused by a novel small insertion mutation in the GLA gene.     

Comprehensive mutation screening in 55 probands with type 1 primary hyperoxaluria shows feasibility of a gene-based diagnosis

Mutations in AGXT, a locus mapped to 2q37.3, cause deficiency of liver-specific alanine:glyoxylate aminotransferase (AGT), the metabolic error in type 1 primary hyperoxaluria (PH1). Genetic analysis of 55 unrelated probands with PH1 from the Mayo Clinic Hyperoxaluria Center, to date the largest with availability of complete sequencing across the entire AGXT coding region and documented hepatic AGT deficiency, suggests that a molecular diagnosis (identification of two disease alleles) is feasible in 96% of patients. Unique to this PH1 population was the higher frequency of G170R, the most common AGXT mutation, accounting for 37% of alleles, and detection of a new 3' end deletion (Ex 11_3'UTR del). A described frameshift mutation (c.33_34insC) occurred with the next highest frequency (11%), followed by F152I and G156R (frequencies of 6.3 and 4.5%, respectively), both surpassing the frequency (2.7%) of I244T, the previously reported third most common pathogenic change. These sequencing data indicate that AGXT is even more variable than formerly believed, with 28 new variants (21 mutations and seven polymorphisms) detected, with highest frequencies on exons 1, 4, and 7. When limited to these three exons, molecular analysis sensitivity was 77%, compared with 98% for whole-gene sequencing. These are the first data in support of comprehensive AGXT analysis for the diagnosis of PH1, obviating a liver biopsy in most well-characterized patients. Also reported here is previously unavailable evidence for the pathogenic basis of all AGXT missense variants, including evolutionary conservation data in a multisequence alignment and use of a normal control population.