Sun X M, Patel D D, Knight B L, Soutar A K
Lipoprotein Team, Hammersmith Hospital, London, UK.
Arterioscler Thromb Vasc Biol. 1997 Nov;17(11):3092-101. doi: 10.1161/01.atv.17.11.3092.
In this study we have analyzed the genetic defect in 42 patients with a diagnosis of heterozygous familial hypercholesterolemia (FH) by Southern blotting, SSCP, and sequencing of PCR-amplified fragments of genomic DNA or sequencing of RT-PCR products from mRNA in cultured cells. The apoB Arg3500Gln mutation was identified in five patients. A molecular defect in the LDL-receptor gene was confirmed in 23 patients; 16 of these mutations have not been described before. No defect in the coding region, intron:exon junctions or proximal promoter of the LDL-receptor gene or in the region of the apoB gene coding for the LDL-receptor binding domain was found in the remaining 14 patients. LDL-receptor activity and protein content of cultured lymphoblasts from the patients was significantly lower in cells from patients with severe rather than mild LDL-receptor mutations. Cells from four patients with no detectable defect showed reduced LDL receptor activity compared with eight normal cell lines, whereas six others had reduced LDL-receptor activity but LDL-receptor protein content within the normal range. Cells from four patients appeared to have normal LDL-receptor function. Cells from two patients with a defined defect also had LDL-receptor activity within the normal range. The findings demonstrate the problems involved in the genetic diagnosis of FH in patients.
在本研究中，我们通过Southern印迹法、单链构象多态性分析（SSCP）以及对基因组DNA的PCR扩增片段进行测序或对培养细胞中mRNA的RT-PCR产物进行测序，分析了42例诊断为杂合子家族性高胆固醇血症（FH）患者的基因缺陷。在5例患者中鉴定出载脂蛋白B（apoB）的Arg3500Gln突变。在23例患者中证实了低密度脂蛋白受体（LDL受体）基因存在分子缺陷；其中16种突变此前尚未见报道。在其余14例患者中，未在LDL受体基因的编码区、内含子：外显子连接处或近端启动子以及apoB基因中编码LDL受体结合域的区域发现缺陷。与轻度LDL受体突变患者的细胞相比，重度LDL受体突变患者培养的成淋巴细胞中LDL受体活性和蛋白质含量显著降低。与8个正常细胞系相比，4例未检测到缺陷的患者的细胞显示LDL受体活性降低，而另外6例患者的LDL受体活性降低，但LDL受体蛋白质含量在正常范围内。4例患者的细胞似乎具有正常的LDL受体功能。2例有明确缺陷的患者的细胞LDL受体活性也在正常范围内。这些发现表明了FH患者基因诊断中存在的问题。
