摘要
家族性高胆固醇血症(hypercholesterolemia familial, FH)是由于低密度脂蛋白受体(low density lipoprotein receptor, LDLR)基因突变导致的常染色体显性遗传性疾病, 临床上表现为多发黄色瘤、高水平血浆 LDL、早发性冠心病及有阳性家族史。本研究通过临床症状结合血脂测定诊断出一个 FH 家系, 其纯合子 FH 患者的血浆总胆固醇水平高达 19.05 mmol/L, LDL 达17.06 mmol/L, 并有黄色瘤; 而杂合子 FH 患者的血浆总胆固醇水平为 7.96 mmol/L, LDL为5.55 mmol/L, 并有心绞痛症状和黄色瘤。我们对该FH 家系患者LDLR 基因的PCR 扩增DNA片段进行测序, 发现纯合子FH 患者LDLR 基因Exon4 区域内发生了GAG683GCG 突变, 即编码 LDLR 第 683 位的谷氨酸被丙氨酸替换, 而杂合子 FH 患者该位点呈现杂合突变。此基因型与临床诊断遗传谱完全一致。同时, 利用获得Epstein-Barr(EB)病毒转化型人永生淋巴细胞株(EBV-Ls)与荧光探针DiI标记的LDL结合反应, 再通过流式细胞仪检测结果显示, 具有功能性LDLR 的EBV-Ls 细胞比例, 在纯合子FH 患者(7.02%)和杂合子FH 患者(62.64%)均比健康对照者(84.69%)低, 纯合子FH 患者LDLR 活性仅为健康对照者的8.29%、而杂合子FH 患者LDLR 活性约为健康对照者的73.96%, 前者呈现非常显著的降低?
Family hypercholesterolemia (FH) is a genetic disorder caused by mutation in the low density lipoprotein receptor (LDLR) gene. It is characterized by a high concentration of low density lipoprotein (LDL), which frequently gives rise to tendon xanthenes and premature coronary artery disease. We studied a FH family ,which was diagnosed by clinical features and blood lipid tests. The Total cholesterol level of the family was 19.05 mmol/L and the LDL level was 17.06 mmol/L in the proband homozygous FH subjects, while the total cholesterol was 7.96 mmol/L and LDL was 5.55 mmol/L in the heterozygous FH subjects. DNA segments amplified with PCR were sequenced in heterozygous and homozygous FH patients. Two novel identical mutation alleles of GAG683GCG, which caused an amino acid change from Glu to Ala, were detected in Exon4 of LDL receptor gene in homozygous proband. DNA sequencing revealed that the proband’s parents were heterozygotes with the same mutational alleles as the proband. These results are in coincidence with the clinical diagnoses. Moreover Epstein-Barr virus transformed lymphocytes (EBV-Ls) were derived by routine virus infection transforming protocol. The cells bounded with the fluorescently conjugated LDL were measured by fluorescence flow cytometry. The ratios of functional LDLR in EBV-Ls originated from homozygous FH, heterozygous FH and normal control were 7.02%, 62.64% and 84.69%, respectively. As a result, the homozygous FH patient’s LDLR had 8.29% and the heterozygous FH patient’s LDLR had 73.96% of the activity of the control. It is apparent that LDL receptor activity of homozygous FH subject is significantly lower than normal control. The data from fluorescence flow cytometry analysis of EBV-Ls strongly support the clinical diagnoses and the results of DNA sequencing.In accordance with the updated version of UMD-LDLR, the mutant GAG683GCG in Exon4 of LDLR gene which we have identified is a novel mutation of the LDLR gene in human with hypercholesterolemia.
出处
《生理学报》
CAS
CSCD
北大核心
2004年第5期566-572,共7页
Acta Physiologica Sinica
