novel mutation of the LDL receptor gene leading to familial hypercholesterolemia

In China, about 1 million people are expected to suffer from familial hypercholesterolemia (FH), with a similar prevalence of FH to that in Caucasian populations. The mutations underlying FH in China are largely unknown because only a few studies have been conducted. In the present study, DNA sequencing analysis was used to scan the low-density lipoprotein receptor (LDLR) and ApoB100 genes in a Chinese family with clinically diagnosed FH. The results showed that the proband had abnormal patterns at nucleotide 517 of exon 4 due to a C/T heterozygosity, and at 1757 of exon 12 due to an A/C heterozygosity in the LDLR gene. Two mutations, C152R and S565X, were identified in the LDLR protein of the proband. DNA analysis of other family members showed that the two mutations should be located in different alleles of the proband. By flow cytometry analysis, the p.S565X mutant receptor displays reduced binding and internalization activity (16 and 19%, respectively) compared with the wild-type receptor. The proband is a compound heterozygote due to the C152R and S565X mutations, which are the possible molecular mechanisms of the etiology of FH in this family.