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目的通过对1例伴血清胆固醇水平极度增高的疑诊为家族性高胆固醇血症(FH)的多发性皮肤黄瘤病患儿及其2代家系成员进行基因检测和系谱分析,探讨多发性皮肤黄瘤病的发病机制。方法收集1例多发性皮肤黄瘤病患儿的家系2代共5例血标本及临床资料,对其家系成员进行血脂测定;对患儿行心电图、血管超声、心脏彩超和冠脉CT造影检查;酚-氯仿抽提法提取患儿及家系成员基因组DNA,应用PCR-单链构象多态性(PCR-SSCP)分析结合DNA直接测序方法 ,检测其低密度脂蛋白受体(LDLR)基因的全部18个外显子和启动子,以及载脂蛋白B(apoB100)R3500Q位点;核苷酸序列分析结果与GenBank比对,寻找突变。结果 1.该患儿父母胆固醇水平均高于正常上限。2.该患儿双侧颈总动脉分叉处中段内-中膜轻度增厚,局部可见强回声斑块;左房轻度增大,二尖瓣轻度返流,冠状动脉血流储备减低;冠状动脉前降支中段轻-中度狭窄。3.该家系排除apoB100基因R3500Q突变。4.核苷酸序列分析证实先证者LDLR基因第13外显子发生D601Y纯合突变,为1864位G>T碱基置换,导致天冬氨酸改变为脯氨酸;患儿父母LDLR基因第13外显子均发生D601Y杂合突变;患儿2个姐姐未检测到突变。结论该例多发性黄瘤病患儿确诊为纯合子FH,其LDLR基因存在D601Y纯合突变分别来源于父系和母系的遗传,该突变可能为该家系中FH的致病突变。
Objective To investigate the genetic and pedigree characteristics of 1 case of multiple cutaneous xanthoma and its second generation pedigrees suspected to be familial hypercholesterolemia (FH) with a high serum cholesterol level. The pathogenesis of xanthoma. Methods A total of 5 blood samples and clinical data of one pedigree of children with multiple cutaneous xanthoma were collected for blood lipid analysis of their pedigrees. Electrocardiogram, echocardiography, echocardiography and coronary CT angiography The genomic DNA of children and their pedigree was extracted by phenol-chloroform extraction. PCR-SSCP and DNA direct sequencing were used to detect the expression of low density lipoprotein receptor (LDLR) gene All 18 exons and promoters, and R3500Q site of apolipoprotein B (apoB100). The results of nucleotide sequence analysis were compared with GenBank to find the mutation. Results 1. The children’s cholesterol levels were higher than the normal upper limit. The bilateral middle carotid artery bifurcation in the middle of the media - mild in the media thickening, the local visible hyperechoic plaques; slight left atrium enlargement, mild mitral regurgitation, coronary flow reserve Reduce; middle anterior descending coronary artery mild to moderate stenosis. The family excluded apoB100 gene R3500Q mutation. Nucleotide sequence analysis confirmed the proband’s LDLR gene exon 13 D601Y homozygous mutation, 1864 G> T base substitution, resulting in aspartic acid to proline; parents of children with LDLR gene D601Y heterozygous mutation occurred in the 13th exon; 2 siblings did not detect the mutation. Conclusions The diagnosis of HNH in children with multiple xanthoma is homozygous FH. The D601Y homozygous mutation of LDLR gene is derived from the inheritance of paternal and maternal origins, respectively. This mutation may be the causative mutation of FH in this pedigree.