Hsia S H, Connelly P W, Hegele R A
Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada.
J Investig Med. 1995 Apr;43(2):187-94.
An adolescent female who presented with type III hyperlipoproteinemia was found to have an E3/2 phenotype by isoelectric focusing while restriction isotyping using HhaI revealed a pattern compatible with classical E3/3. Studies were carried out to determine the nature of the patient's apolipoprotein E abnormality.
A 244 bp fragment of exon 4 of apolipoprotein E was amplified by the polymerase chain reaction (PCR). Restriction isotyping was carried out with BbvI and Fnu4HI and results were confirmed by direct sequencing.
The patient was found to be heterozygous for a C-->T transition at the first base of codon 145, resulting in a substitution of cysteine for arginine (R145C) which completely explained the discrepancy between the isoelectric focusing and HhaI restriction isotyping. We noted that the DNA change altered palindromic recognition sites for the endonucleases BbvI and Fnu4HI.
Digestion with BbvI or Fnu4HI allows for rapid restriction isotyping for the rare apolipoprotein E R145C mutation associated with hyperlipidemia.
一名患有III型高脂蛋白血症的青春期女性，通过等电聚焦发现其具有E3/2表型，而使用HhaI进行的限制性分型显示出与经典E3/3相符的模式。开展了研究以确定该患者载脂蛋白E异常的性质。
通过聚合酶链反应（PCR）扩增载脂蛋白E第4外显子的244 bp片段。用BbvI和Fnu4HI进行限制性分型，并通过直接测序确认结果。
发现该患者在密码子145的第一个碱基处存在C→T转换的杂合性，导致半胱氨酸替代精氨酸（R145C），这完全解释了等电聚焦和HhaI限制性分型之间的差异。我们注意到DNA变化改变了内切酶BbvI和Fnu4HI的回文识别位点。
用BbvI或Fnu4HI消化可实现对与高脂血症相关的罕见载脂蛋白E R145C突变的快速限制性分型。
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