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新的突变类型一例

目的：分析一例家庭性高胆固醇血症患的低密度脂蛋白受体基因突变位点。方法：以患儿的基因组DNA为模板，用聚合酶链反应（PCR）扩增该基因的18个外显子。用单链构象多态性（SSCP）方法分析检测PCR产物，对电泳结果异常进行DNA测序。结果：单链构象多态性分析发现患儿第10外显子存在一异常条带。DNA测序证实患儿第10外显子发生N515S纯合错义突变。结论：该病例为一个新的LDLR突变位点；聚合酶链反应－单链构象多态性分析（PCR－SSCP）可用于该突变位点的诊断。     

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。     

家族性高胆固醇血症患者低密度脂蛋白受体基因新突变一例

目的 分析中国家族性高胆固醇血症（FH）患儿低密度脂蛋白受体（LDL－R）基因突变的情况，并为在婴幼儿时期此病的症前筛查提供确诊方法。方法 以患儿及其父母的基因组DNA为模板，首先用聚合酶链反应（PCR）扩增该基因的启动子和全部18个外显子，然后用单链构象多态性（SSCP）方法分析PCR产物，最后对电泳结果异常进行DNA测序。结果 在1个家系中检测出患儿和其父亲LDL－R基因的一种新突变，即在第4外显子的444位碱基发生杂合突变（T→A），相应的氨基酸由半胱氨酸变成终止密码子，其母亲LDL－R基因正常。结论 LDL－R基因此位点的突变可引起FH，PCR－SSCP方法可用于筛查出的高危人群的确诊。     

Low density lipoprotein receptor gene mutations in patients with clinical diagnosis of familial hypercholesterolemia.

Low density lipoprotein receptor (LDLR) gene mutations cause familial hypercholesterolemia which is associated with elevated risk of ischemic heart disease. AIM: To define LDLR gene mutations in unrelated patients with heterozygous familial hypercholesterolemia in Russia. METHODS: PCR- single-strand conformation polymorphism analysis, automated DNA sequencing, and test for the presence of the apolipoprotein (apo) B-3500 mutation known to induce hereditary defect in apo-B-100. RESULTS: We found 6 novel mutations of LDLR gene designated E8X, 230insG, 671_679dupGACAAATCT, W422R, D461Y, and V698L. We also identified three missense mutations - C139G, E207K and R395W, which were previously described in FH patients from western populations. None of the studied persons had apo-B-3500 mutation. CONCLUSION: These findings broaden knowledge on mutations responsible for development of familial hypercholesterolemia and confirm molecular heterogeneity of this disease in Russia.     

家族性高胆固醇血症一家系基因突变分析和临床治疗

目的]总结1例家族性高胆固醇血症(FH)家系的基因突变分析和临床治疗方案。 [方法]先证者因“反复气喘伴胸痛4个月,加重2天”入院,血浆低密度脂蛋白胆固醇(LDLC)异常升高,且早发冠心病,对先证者进行全外显子测序和载脂蛋白E(ApoE)、对氧磷酶1(PON1)、前蛋白转化酶枯草溶菌素9(PCSK9)等位点进行测序分析,针对可疑致病突变在家系成员中进行检测,对先证者及其父亲进行了冠状动脉介入治疗和降脂治疗。 [结果]先证者、其父亲和其儿子在低密度脂蛋白受体(LDLR)基因中均检出了6个突变位点,分别为c.191+13G＞A(rs200621482)、c.1598G＞T(rs200427089)、c.883T＞G(rs553235458)、c.3536A＞G(rs201300867)、c.2215+6G＞A(rs540060615)、c.162+5A＞T(rs146596406)。这3例患者的6个位点均为杂合突变。3例患者的ApoE基因型结果如下:先证者及其儿子的ApoE基因型均为ε3/ε3型,蛋白表型为E3(ApoE2位点为CC型,ApoE4位点为TT型);其父亲的ApoE基因型为ε2/ε3型,蛋白表型为E2(ApoE2位点为CT型,ApoE4位点为TT型)。3例患者的PON1(A575G,rs662)位点基因型均为AG型,3例患者的PCSK9基因型为GG、CC、CC、GG型。基于该家系遗传学检测结果,给予先证者及其父亲个体化的降脂治疗方案,阿托伐他汀钙与依折麦布联合PCSK9抑制剂,且先证者及其父亲成功行冠状动脉介入治疗术,随访两年LDLC控制较好,未出现药物不良反应。 [结论]本研究中该家系患者的LDLR基因均发现6个位点突变,其中LDLR c.191+13G＞A、c.162+5A＞T在国内尚未见报道,丰富了中国人群的LDLR基因突变谱。本研究有利于阐明FH的发病机制,进一步指导FH患者的临床治疗。     

家族性高胆固醇血症患者低密度脂蛋白受体基因热点突变Taqman MGB探针检测方法的建立及应用

目的:建立Taqman MGB探针实时荧光定量PCR检测家族性高胆固醇血症(FH)患者低密度脂蛋白受体(LDLR)基因热点突变的简便方法。方法:1入选94例临床确诊FH患者为研究对象,30例健康人作为阴性对照及明确存在LDLR基因热点突变W462X、A606T和D601Y的FH患者各1例作为阳性对照,分别提取外周血DNA;2应用Primer Premier v3.0软件设计3个热点突变的特异性引物和Taqman MGB探针;3运用Taqman探针实时荧光定量PCR方法,对3例阳性对照及30例健康对照进行检测,检验方法的准确性;4同法检测94例确诊FH患者的基因组DNA;5运用Touch-down PCR方法对发现突变患者进行一代测序验证。结果:13例阳性对照均检测到相应突变,30例健康对照均未检测到突变,证实此方法能够准确检测到基因突变位点;294例确诊FH患者中发现13例W462X、3例A606T、1例D601Y,初步计算3个热点突变约占全部FH患者的18.1%;3对发现突变的17例患者进行一代测序验证,结果完全一致。结论:成功建立Taqman MGB探针实时荧光定量PCR方法,为FH患者LDLR基因热点突变的检测提供了快速可靠的技术手段。     

Additive effect of mutations in LDLR and PCSK9 genes on the phenotype of familial hypercholesterolemia

Patients homozygous or compound heterozygous for LDLR mutations or double heterozygous for LDLR and apo B R3500Q mutation have higher LDL-C levels, more extensive xanthomatosis and more severe premature coronary disease (pCAD) than simple heterozygotes for mutations in either these genes or for missense mutations in PCSK9 gene. It is not known whether combined mutations in LDLR and PKCS9 are associated with such a severe phenotype. We sequenced Apo B and PCSK9 genes in two patients with the clinical diagnosis of homozygous FH who were heterozygous for LDLR gene mutations. Proband Z.P. (LDL-C 13.39 mmol/L and pCAD) was heterozygous for an LDLR mutation (p.E228K) inherited from her father (LDL-C 8.07 mmol/L) and a PCSK9 mutation (p.R496W) from her mother (LDL-C 5.58 mmol/L). Proband L.R. and her sister (LDL-C 11.51 and 10.47 mmol/L, xanthomatosis and carotid atherosclerosis) were heterozygous for an LDLR mutation (p.Y419X) inherited from their mother (LDL-C 6.54 mmol/L) and a PCSK9 mutation (p.N425S) probably from their deceased father. The LDL-C levels in double heterozygotes of these two families were 56 and 44% higher than those found in simple heterozygotes for the two LDLR mutations, respectively. The two PCSK9 mutations are novel and were not found in 110 controls and 80 patients with co-dominant hypercholesterolemia. These observations indicate that rare missense mutations of PCSK9 may worsen the clinical phenotype of patients carrying LDLR mutations.     

Exon-Alu recombination deletes 5 kilobases from the low density lipoprotein receptor gene, producing a null phenotype in familial hypercholesterolemia.

Among patients with familial hypercholesterolemia, half of the mutant alleles at the low density lipoprotein (LDL) receptor locus produce no immunologically detectable protein. To determine the molecular basis for one such null allele, we have cloned an abnormally short restriction fragment from the genomic DNA of one patient. The DNA sequence revealed a 5-kilobase deletion that joins a coding sequence in exon 13 to an Alu repetitive element in intron 15. The deletion joint is flanked by two inverted repeats that could potentially form a double stem-loop structure that might have predisposed to this deletion. A similar double stem-loop structure can be drawn for a previously described deletion in the LDL receptor gene and for a deletion in the beta-globin gene cluster. We speculate that such double stem-loop structures might contribute to the formation of large deletions in the human genome.     

Mutations in the LDL receptor gene in four Chinese homozygous familial hypercholesterolemia phenotype patients

Background and aimsFamilial hypercholesterolemia (FH) is an autosomal dominant disorder of lipoprotein metabolism caused by mutations in the low-density lipoprotein receptor (LDL-R) gene, leading to elevated levels of cholesterol and an increased risk of coronary heart disease. In this article, from four homozygous FH phenotype probands we identified disease causing mutations and analyzed the relationship between genotype and phenotype.Methods and resultsDNA sequencing identified five LDL-R point mutations in four unrelated families. We found a novel homozygous mutation (C210R), a homozygous mutation at W462X, a compound heterozygous mutation of C122Y and T383I, and a G>A intron 3 splice site homozygous mutation. The functional alteration caused by the novel C210R mutation was confirmed by FACS analysis. Four probands have high low-density lipoprotein cholesterol (LDL-C) levels, ranging from 14.65 to 27.66 mmol/L. Their heterozygous parents had relatively low levels. B-mode ultrasound supplemented by Doppler was used to examine aortic/mitral valve structural alterations and carotid intima-media thickness (ITM) in all probands. The ITM values were between 1.2 and 2.3 mm, much higher than the normal value of <0.8 mm.ConclusionOur data demonstrated that all the probands were associated with severe hypercholesterolemia, thick carotid IMT and a low CFVR (coronary flow velocity reserve) value. The novel mutation (C120Y) is a disease causing mutation.     

A functional polymorphism in the promoter region of the microsomal triglyceride transfer protein (MTP -493G/T) influences lipoprotein phenotype in familial hypercholesterolemia

The microsomal triglyceride transfer protein (MTP) has a key function in intracellular apolipoprotein (apo) B lipidation and secretion of very low density lipoprotein (VLDL). A recently discovered functional polymorphism in the promoter of the MTP gene (-493G/T) affects the plasma concentration of low density lipoprotein (LDL) cholesterol and the VLDL distribution between large and small particle species in healthy men. This phenotype is likely to be explained by an effect on VLDL synthesis. Against this background, we studied the effect of the MTP-493G/T polymorphism in a large cohort (217 men and 211 women) with heterozygous familial hypercholesterolemia (FH). A 40% to 50% lower serum triglyceride level was observed in homozygous carriers of the MTP-493 T allele (T/T, 0.93+/-0.34; G/T, 1.54+/-1.40; and G/G, 1.56+/-1.24 mmol/L; T/T vs G/T P=0.04, T/T vs G/G P=0.02). In contrast to the situation in healthy subjects, the MTP promoter polymorphism did not have a significant effect on the LDL cholesterol levels in FH subjects, although the same trend was observed (T/T, 7.31+/-1.87; G/T, 7. 80+/-2.12; and G/G, 7.91+/-2.31 mmol/L, NS). Adjustment for the apo E gene polymorphism by inclusion of subjects homozygous for the apo E3 allele only revealed a reciprocal high density lipoprotein cholesterol-elevating effect (T/T, 1.41+/-0.73; G/T, 1.18+/-0.27; and G/G, 1.16+/-0.29 mmol/L; T/T vs G/T P=0.06, T/T vs G/G P=0.04). This effect seemed to be sex-specific because it was accounted for by the female patients. In conclusion, the LDL cholesterol-lowering effect of the rare MTP gene promoter variant (MTP-493T) present in healthy subjects is shifted to a triglyceride-lowering effect in FH. These data suggest that the MTP gene has a role in modulating the clinical phenotype of FH.     

Identification and 3D architecture analysis of the LIPC gene mutation in a pedigree with familial hypercholesterolemia-like phenotype

<正>Objective To identify and analyze 3D architecture of the mutational sites of susceptible genes in a pedigree with familial hypercholesterolemia-like phenotype(FHLP).Methods This is a case series study.A pedigree with suspected familial hypercholesterolemia was surveyed.The proband was admitted in Beijing Anzhen Hospital in April 2019.Whole-exome sequencing was performed to determine the mutational sites of susceptible genes in the proband.Polymerase chain reaction (PCR)sequencing was us...     

家族性混合型高脂血症与脂蛋白脂酶基因的连锁分析

目的 探讨脂蛋白脂酶基因与家族性混合型高脂血症是否连锁，以期发现家族性混合型高脂血症遗传易感位点。方法 从北京地区搜集12个（81人）家族性混合型高脂血症家系选择脂蛋白脂酶基因及其附近的微卫星遗传标记（LPLGZ14／15与D8S282）进行连锁分析。结果 CENEHUNTER软件包多点连锁分析显示微卫星遗传标记最大LOD score(HLOD)值如下：HLODLPLGZ14／15＝－8．9及HLODD8S282＝－10．5。结论 中国北京地区家族性混合型高脂血症家系提示，脂蛋白脂酶基因不是影响家族性混合型高脂血症表型的遗传易感基因。