Gene Mutation Analysis of A Child with Familial Hypercholesterolemia and His Family / 实用儿科临床杂志

ABSTRACT

Objective To screen the mutation of certain gene of a 10-years-old boy with multiple xanthomas and very high level of cholesterol who could be diagnosed as homozygous familial hypercholesterolemia (FH),to explore the relationship between the genotype and phenotype,and to discuss the molecular pathologic mechanism.Methods The basic information of life styles were asked from the boy and his familial members.The blood was drown to examine the lipid and genes.The boy was examined with electrocardiogram examination,ultrasonography and coronary CT angiography (CTA) to evaluate the degree of atherosclerosis.Peripheral blood DNA of the boy and his parents were extracted by phenol-chloroform method and investigated for mutations of promoter and all 18 exons of low density lipoprotein receptor(LDLR) gene.Screening was carried out by using Touch-down polymerase chain reaction (PCR) and single strand conformation polymorphism(PCR-SSCP),combined with DNA sequence analysis.In addition,the apolipoprotein B100 gene(apoB100) for known mutations (R3500Q) which caused familial defective apoB100 was screened by PCR-DNA sequence analysis.Results 1.The level of cholesterol of his parents were higher than the normal.2.Several clinical manifestations of atherosclerosis were detected from that boy.Increased intima-media thickness and plaques were detected in the common carotid artery.Mitral valve regurgitation was found by echocardiography.Coronary stenosis was confirmed by CTA.3.No mutations R3500Q of apoB100 was observed.4.A homozygous mutation in exon13 of the LDLR gene (D601Y) were identified in the boy and his parents harbour D601Y heterozygous mutation due to a single base pair substitution of G for T in the codon for residue 1864.Conclusions The final diagnosis of the boy with multiple xanthomas was homozygous FH.His disease was caused by D601Y homozygous mutation in exon13 of the LDLR gene inherited from his heterozygous parents.