家族性高胆固醇血症低密度脂蛋白受体基因突变分析

目的:检测1例家族性高胆固醇血症(FH)先证者及其4代家系成员低密度脂蛋白受体(LDL-R)基因突变,探讨该家族FH可能发病分子机制.方法:收集先证者及其家系成员临床资料和基因组DNA,以基因组DNA为模板,用PCR方法扩增LDL-R基因的启动子和全部18个外显子,PCR产物进行限制性内切酶技术结合DNA测序,核苷酸序列分析结果与Gen Bank比对寻找突变;采用PCR-DNA测序技术检测apoB100基因R3500Q、R3531C和R3500W位点以及枯草溶菌素转化酶9(PCSK9)基因,以排除家族性apoB100缺陷症和PCSK9基因突变.结果:先证者及其部分家系成员第6号外显子发生Cys276X杂合无义突变,为半胱氨酸改变为提前终止密码子,使终止密码子在第276位提前出现,为致病性突变,国内尚无报道;另外,第15号外显子发生Arg744Arg同义突变.其母未发现上述突变,未检测出患者及其家系apoB100基因R3500Q、R3531C和R3500W突变以及枯草溶菌素转化酶9基因突变.结论:此患者及家系LDL-R基因存在Cys276X无义突变,可能是FH的致病突变,该突变是我国FH患者LDLR基因的一种新突变类型.     

家族性高胆固醇血症患者低密度脂蛋白受体新突变类型与表型关系的研究

目的　检测中国汉族家族性高胆固醇血症 (FH)家系低密度脂蛋白受体 (LDLR)基因突变类型 ,研究基因型与表型间的关系 ,探讨FH发病的分子病理机制。方法　先证者及家系成员进行血脂测定、心电图、心脏及大血管彩色多普勒超声检查后采用聚合酶链反应 ( polymerasechainreaction ,PCR) 变性高效液相色谱 (DHPLC)法结合扩增产物直接序列分析检测LDLR基因启动子和全部 18个外显子片段 ,结果与GenBank公布的该基因正常序列比对找出突变并检索FH突变数据库(www .ucl.ac .uk/fh)。此外 ,采用PCR 限制性内切酶技术 ,检测载脂蛋白B10 0 (ApoB10 0 )基因Q35 0 0R突变 ,以排除家族性ApoB10 0 缺陷症 (FDB)。结果　DHPLC分析发现该患儿及其父母LDLR基因第 3外显子存在一异常波峰 ,DNA测序证实该患儿第 3内含子 5′剪接位点存在G→A纯合剪接突变 ,其父母相同位点表现为野生型和突变型杂合现象 ;同时未检测出患儿及其父母ApoB10 0Q35 0 0R突变。结论　国内首次发现LDLR基因第 3内含子G→A纯合剪接突变 ;该突变可能是FH发病的分子基础并导致其严重的临床表型 ;PCR DHPLC法可用于FH可疑人群的确诊     

家族性高胆固醇血症患者低密度脂蛋白受体基因复合纯合突变一例

目的 检测家族性高胆固醇血症(FH)患者低密度脂蛋白受体(LDL—R)基因点突变，分析基因型与临床表型间的关系，探讨其分子病理机制。方法以1例临床诊断为FH纯合子患儿及其父母的基因组DNA为模板，用降落PCR方法，在同一程序中分别对LDL—R基因的启动子和全部18个外显子片段进行扩增，琼脂糖凝胶电泳检测，扩增产物直接进行核苷酸序列分析，并检索FH突变数据库(www．ucl．ac．uk／fh)。此外采用PCR-限制性内切酶技术，检测载脂蛋白(Apo)B100基因Q3500R突变，以排除家族性Apo B100缺陷症。结果该患儿及其父亲第4外显子发生Cys^122→Tyr(C122Y)杂合错义突变，同时患儿及其母第9外显子发生Thr^273→Ile(17383I)杂合错义突变，因此该患儿LDLR基因第4、9外显子各存在一个杂合突变，上述突变尚未在FH突变数据库见到。未检测出患儿及其父母Apo B100Q3500R突变。结论此患儿为LDL—R基因存在C122Y、T3831合纯合突变并分别来自其父母；以上两位点突变可引起FH；是FH患者LDL-R基因的一种新突变类型。     

姐妹2人同患家族性高胆固醇血症家系LDL-R基因突变分析

目的:对临床确诊的家族性高胆固醇血症(FH)两姐妹及其家系成员进行低密度脂蛋白受体(LDL-R)基因突变分析,探讨其发病机制。方法:提取患者外周血基因组DNA,聚合酶链反应分别扩增启动子和18个外显子片断,采用单链构象多态性(PCR-SSCP)结合银染技术,对异常电泳条带进行核苷酸序列分析。结果:姐妹2人及其父亲,叔叔,祖母均发现LDL-R基因第13外显子存在一个错义突变,与GeneBank对照证实第1879位G→A碱基置换,氨基酸的改变为丙氨酸→苏氨酸(A606T突变),其母亲和女儿经测序并未发现此突变位点。结论:姐妹2人均为LDL-R基因存在A606T杂合错义突变,并均来自其父系亲属;可能是该家系发病的分子基础。     

姐妹2人同患家族性高胆固醇血症家系LDL-R基因突变分析

目的：对临床确诊的家族性高胆固醇血症（FH）两姐妹及其家系成员进行低密度脂蛋白受体（LDL-R）基因突变分析,探讨其发病机制。方法：提取患者外周血基因组DNA,聚合酶链反应分别扩增启动子和18个外显子片断,采用单链构象多态性（PCR-SSCP）结合银染技术,对异常电泳条带进行核苷酸序列分析。结果：姐妹2人及其父亲,叔叔,祖母均发现LDL-R基因第13外显子存在一个错义突变,与GeneBank对照证实第1879位G→A碱基置换,氨基酸的改变为丙氨酸→苏氨酸（A606T突变）,其母亲和女儿经测序并未发现此突变位点。结论：姐妹2人均为LDL-R基因存在A606T杂合错义突变,并均来自其父系亲属；可能是该家系发病的分子基础。     

低密度脂蛋白受体基因突变类型的筛查

目的调查我国家族性高胆固醇血症(FH)患者低密度脂蛋白受体基因突变类型。方法以患者的基因组DNA为模板,用聚合酶链反应扩增该基因的18个外显子。用单链构象多态性方法分析检测PCR产物,对电泳结果异常者进行DNA测序;错配引物PCR引入Msp Ⅰ酶切位点检测最常见的载脂蛋白B基因突变类型R3500Q。结果经单链构象多态性分析发现,7个先证者有异常电泳条带出现。DNA测序证实,先证者存在9个突变位点。经文献检索发现除C255R外,其余均系尚未报道的新突变类型。在所有FH患者中未检测出载脂蛋白B基因突变。结论中国人FH患者可能存在独特的低密度脂蛋白受体基因突变谱。     

家族性高胆固醇血症基因突变及临床表型研究

目的 筛查家族性高胆同醇血症家系载脂蛋白(Apo)B100基因及低密度脂蛋白受体(LDLR)基因突变,并探讨其临床表现.方法 采用PCR扩增ApoB100基因包含3500、3501、3531和3480位点的序列;扩增LDLR启动子和全部18个外显子片段,产物电泳鉴定后直接序列分析,结果 与GenBank公布的基因正常序列比对,找出突变.结果 该家系LDLR基因第10外显子的第1581位碱基发生G＞A突变,导致G496E突变;未检出ApoB100基因突变.结论 此突变为一新突变,为该家系致病性突变.

Abstract：

Objective To investigate the low density lipoprotein receptor (LDLR)gene and apolipoprotein (Apo) B gene mutation in a Chinese family with familial hypercholesterolemia(FH) and give the kindrids clinical check-ups. Methods After physical examination, the kindreds underwent ECG and ultrasound checks. Blood samples were tested for lipid profiles. The promoter and all eighteen exons of LDLR gene were investigated by using PCR and agarose gel electrophoresis in combination with DNA sequence analysis. The results were compared with the normal sequences in GenBank and FH database ( www. ucl. ac. uk/fh ) to find mutations. In addition, the apolipoprotein B100 gene for known mutations (R3500Q,R3531C,R3501W and R3480W)that cause familial defective ApoB100 (FDB)was also tested using the same method. Results A novel homozygous G ＞ A mutation at the 1581 bp of exon 10 was detected in the proband and his siblings. It caused a substitution of amimo acid Glu to Gly at codon 496. A novel heterozygous G ＞A mutation at the 1581 bp of exon 10 was detected in his parents. No mutations of R3500Q,R3531C,R3501W and R3480W of ApoB100 were observed. ECGs were normal. Atherosclerosis were found in all family members by ultrasound checks. Conclusions The homozygous G ＞ A mutation at the 1581 bp of exon 10 was first determined in our country. The change of amino acid Glu to Gly is responsible for FH of the family. The type of the gene mutation was not found in the FH database( www. ucl.ac. uk/ih). It's a new type of LDLR mutation.     

家族性高胆固醇血症低密度脂蛋白受体基因新突变位点的鉴定——附1例报告

目的 分析家族性高胆固醇血症(FH)患者低密度脂蛋白受体(LDLR)的基因突变.方法 收集2004年10月至2006年10月在北京大学第一医院诊断的1例FH患者,以同期北京大学第一医院门诊51名血脂正常者为对照.以患者的基因组DNA为模板,用聚合酶链反应扩增该基因的启动子和18个外显子,对PCR产物进行DNA测序.结果 DNA测序结果发现先证者和其母亲LDLR第4外显子的一种新突变,即编码区外显子第385位核苷酸由G突变为T(G385T),相应的第108位氨基酸由天冬氨酸变化为酪氨酸(D108Y).结论 LDLR基因此位点的突变可引起FH,该突变为LDLR基因的一种新突变.     

新突变致复合杂合子家族性高胆固醇血症家系的基因检测

目的对临床诊断为遗传性高胆固醇血症纯合子患者所在家系成员的相关基因进行突变检测和分析,探讨该病的分子诊断方法和发病的可能分子机制。方法以该家系中3代共6人的基因组DNA为模板,用PCR对低密度脂蛋白受体（LDLR）基因的全部18个外显子和启动子以及载脂蛋白B-100（Apo B-100）基因3500-3531区域进行扩增,琼脂糖凝胶电泳鉴定后对PCR产物直接测序。测序结果与Gene Bank中该基因的正常序列对比找出突变,结合该家系成员临床表型证实突变。结果在ApoB-100的3500-3531区域未发现突变,而在先证者LDLR基因的第4外显子发现新的点突变685delA杂合性腺嘌呤缺失和386A〉G杂合错义突变,其父存在685delA杂合性腺嘌呤缺失,其母存在386A〉G杂合错义突变。结论证实家系先证者是存在LDLR突变的复合杂合子,发现的新的LDLR基因突变位点386A〉G和685delA分别来源于父系和母系的遗传,可能是该家系发病的分子基础。     

甲状腺激素受体β基因H435Y突变所致甲状腺激素抵抗综合征:一家系研究

[提要]对一个包括先证者在内共28位成员的甲状腺激素抵抗综合征家系进行临床调查,并提取先证者及其家系14位成员(其他13位成员拒绝抽血)外周血白细胞基因组DNA,对甲状腺激素受体(thyroid hormone receptor,TR)β基因的第1～ 10外显子进行PCR扩增,PCR产物进行DNA测序检测突变位点.测序结果显示,该家系中有3名成员TRβ第10外显子1 303位核苷酸发生C转换为T的错义突变,使该位点编码的氨基酸由组氨酸变为酪氨酸(H435Y),此突变为杂合子突变,可能导致了甲状腺激素抵抗综合征的发生.     

Rapid screening for specific mutations in patients with a clinical diagnosis of familial hypercholesterolaemia.

We describe a rapid screening procedure to identify known DNA sequence changes in individuals diagnosed as having heterozygous familial hypercholesterolaemia (FH). The screening is made possible by combining a rapid DNA extraction protocol and small scale polymerase chain reaction DNA amplification, followed by oligonucleotide melting or restriction enzyme digestion. We have screened for two different mutations; firstly a mutation in the apolipoprotein B (apo B) gene that results in the substitution of glutamine (Gln) for arginine (Arg) at amino acid residue 3500 (apo B3500 mutation). Apo B is the principal component of the protein moiety of low density lipoprotein (LDL) and the mutation reduces the affinity for the LDL receptor (LDL-R). Secondly we have screened for a point mutation in the LDL-R gene itself that creates a new Pst I restriction enzyme site. This mutation in the LDL-R gene (LDL-R664 mutation) results in the substitution of leucine (Leu) for proline (Pro) at amino acid 664 and is known to slow processing of the LDL-R precursor to the mature form and to reduce the affinity of the receptor on the cell surface for LDL. In 77 unrelated patients with a clinical diagnosis of FH two out of 77 (2.6%) were positive for the apo B3500 mutation. Three (3.9%) were positive for the LDL-R664 mutation. Thus these two mutations might account for 5-6% of patients in the U.K. with a clinical diagnosis of FH (5000-6000 people).(ABSTRACT TRUNCATED AT 250 WORDS)     

Molecular genetics of familial hypercholesterolaemia in Norway

Objectives. To characterize mutations in the low density lipoprotein (LDL) receptor gene causing familial hypercholesterolaemia (FH) amongst Norwegian patients.
Design. Molecular genetic analyses of the LDL receptor gene have been performed in patients with a clinical diagnosis of FH.
Subjects. A total of 742 probands have been studied. Of these, 476 had a diagnosis of definite FH. The rest had a diagnosis of possible FH.
Results. Twenty-three different mutations in the LDL receptor gene as well as the apolipoprotein B-3500 mutation have been found. Six of the mutations in the LDL receptor gene are novel mutations. A molecular genetic diagnosis was achieved in 295 of the probands with definite FH (62%) and in 317 probands total. Of the 317 probands, 3% carried the apolipoprotein B-3500 mutation. When family members were included, a total of 624 persons carried a mutation in the LDL receptor gene and 20 carried the apolipoprotein B-3500 mutation.
Conclusions. Approximately 5% of Norwegian FH patients have been provided with a molecular genetic diagnosis. Our data suggest that molecular diagnosis of FH in Norway is feasible and should be implemented in clinical medicine.     

Familial hypercholesterolemia in Utah kindred with novel R103W mutations in exon 4 of the LDL receptor gene

Heterozygous familial hypercholesterolemia (FH) is a serious disorder causing twice normal low-density lipoprotein cholesterol levels early in childhood and very early coronary disease in both men and women. Previously published blood cholesterol criteria greatly under-diagnosed new cases of FH among members of known families with FH and over-diagnosed FH among participants of general population screening. Thus, there is a need for accurate and genetically validated criteria for the early diagnosis of heterozygous FH. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To carry out molecular genetic diagnosis of the disease, we screened DNA samples for mutations in all 18 exons and the exon- intron boundaries of the low-density lipoprotein (LDL) receptor gene. Novel point mutations were identified in the proband: a C-to-T transversion at nucleotide position 369, causing substitution of Tryptophan for Arginine at codon 103 in exon 4 of the LDL receptor gene. The SSCP method was used to examine seven members of the family recruited for the diagnosis. This method helped to unequivocally diagnose only the proband as heterozygous for this particular LDL receptor mutation while excluding the remaining six individuals from carrier status with FH.     

FH-Freiburg: a novel missense mutation (C317Y) in growth factor repeat A of the low density lipoprotein receptor gene in a German patient with homozygous familial hypercholesterolemia

We describe the characterization of a novel mutation in the low density lipoprotein receptor (LDL-R) gene in a patient with true homozygous familial hypercholesterolemia (FH). The combined use of denaturing gradient gel electrophoresis (DGGE) and sequencing of genomic DNA revealed a guanine to adenine base substitution at nucleotide position 1013 of the LDL-R cDNA. This point mutation results in a change from cysteine to tyrosine at amino acid residue 317 of repeat A of the epidermal growth factor (EGF) precursor homology domain. Binding, uptake and degradation of iodinated LDL in skin fibroblasts from the homozygous patient were less than 10% of normal. In contrast, binding, uptake and degradation of iodinated VLDL was reduced by only 60, 30, and 38%, respectively. Incubation of the patient's fibroblasts in the presence of cholesterol diminished the residual binding of VLDL by 50%, suggesting that the loss of the highly conserved cysteine at position 317 results in a LDL-R that fails to bind LDL, but retains some ability to bind VLDL by interacting with the apolipoprotein E. Both parents were heterozygous for the C317Y mutation. Interestingly, however, the father presented with markedly elevated levels of triglycerides and VLDL cholesterol, whereas his LDL cholesterol was unexpectedly low. The mother of the index patient had only slightly elevated LDL cholesterol. These observations testify to the biological complexity of genotype-environment interactions in individuals carrying mutations at the LDL-R locus and indicate that genetic analysis importantly complements the clinical and biochemical diagnosis of patients with hyperlipidemia.     

低密度脂蛋白受体功能与基因突变的关系

目的：分析家族性高胆固醇血症低密度脂蛋白受体（LDLR）功能变化,寻找基因突变位点;阐明该基因突变类型对LDLR功能的影响。方法：患儿及其你系、母系三代共30人检查血脂和临床表现,作系谱分析,确定该患儿符合家族性高胆固醇血症纯合子的诊断;培养患儿皮肤成纤维细胞,用受体的放射性配体结合技术,定量测定细胞的LDLR的功能;提取外周血基因组DNA对LDLR基因的相应外显子进行PCR－SSCP及DNA序列分析。结果：系谱分析发现11个杂合子及1个纯合子;纯合子患儿LDLR结合功能基本正常,但其内移和降解功能只有正常人的3．6％及1．7％;DNA测序结果证实患儿第17外显子的第599和600密码子间插入一个碱基G,导致框移突变;第842密码子发生CCA→CCG的无义突变。结论：首次报道了一个新的LDLR突变位点;初步明确该突变位点对患者的影响较为显著。