Identification of a novel mutation at the point of low density lipoprotein receptor gene from a subject with familial hypercholesterolemia
- Author:
- No author available
- Journal Title:
- ACTA PHYSIOLOGICA SINICA
- Issue:
- 5
- DOI:
- 10.3321/j.issn:0371-0874.2004.05.002
- Key Word:
- 家族性高胆固醇血症;低密度脂蛋白受体;Epstein-Barr病毒;永生化淋巴母细胞;流式细胞仪;突变位点
Abstract： 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.这些EBV-Ls细胞LDLR的功能变化分析,有力地支持了该FH家系的临床诊断和DNA测序结果.经查阅最新的UMD-LDLR完全版证实,本研究发现鉴定的GAG683GCG突变是人LDLR基因的新突变位点.
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