Use of Targeted Exome Sequencing in Genetic Diagnosis of Chinese Familial Hypercholesterolemia

Abstract

Familial hypercholesterolemia is an autosomal dominant inherited disease characterized by elevated plasma low-density lipoprotein cholesterol (LDL-C). It is mainly caused by mutations of the low-density lipoprotein receptor (LDLR) gene. Currently, the methods of whole genome sequencing or whole exome sequencing for screening mutations in familial hypercholesterolemia are not applicable in China due to high cost. We performed targeted exome sequencing of 167 genes implicated in the homozygous phenotype of a proband pedigree to identify candidate mutations, validated them in the family of the proband, studied the functions of the mutant protein, and followed up serum lipid levels after treatment. We discovered that exon 9 c.1268 T>C and exon 8 c.1129 T>G compound heterozygous mutations in the LDLR gene in the proband derived from the mother and father, respectively, in which the mutation of c.1129 T>G has not been reported previously. The mutant LDL-R protein had 57% and 52% binding and internalization functions, respectively, compared with that of the wild type. After 6 months of therapy, the LDL-C level of the proband decreased by more than 50% and the LDL-C of the other family members with heterozygous mutation also reduced to normal. Targeted exome sequencing is an effective method for screening mutation genes in familial hypercholesterolemia. The exon 8 and 9 mutations of the LDLR gene were pedigree mutations. The functions of the mutant LDL-R protein were decreased significantly compared with that of the wild type. Simvastatin plus ezetimibe was proven safe and effective in this preschool-age child.

Genetic Basis and Genotype–Phenotype Correlations in Han Chinese Patients with Idiopathic Dilated Cardiomyopathy

“…Targeted next-generation sequencing, which included library construction, capture, and sequencing, was carried out. Targeted gene enrichment was performed with the GenCap Custom Enrichment Kit according to the GenCap protocol, as described previously [27][28][29] . Captured DNA libraries were sequenced with the Illumina HiSeq.…”

The use of targeted exome sequencing in genetic diagnosis of young patients with severe hypercholesterolemia

“…Therefore, there is a pressing clinical incentive to develop effective screening methods420 for the early detection of FH. In a previous study, we used whole exome sequencing and TES to identify patients with HoFH and found that these technologies are useful for providing an accurate genetic diagnosis in patients with severe hypercholesterolemia1011. In the present work, we have analyzed 20 young patients with severe hypercholesterolemia by either array sequencing or TES.…”

“…Subjects attended the atherosclerosis clinic at the Anzhen hospital, Beijing, China, during the period 2003–2015. DNA samples from 12 patients were processed using DNA resequencing array7, samples from 14 patients were processed by targeted exome sequencing10, and samples from 6 patients were processed by both methods. Some probands were reported in previous studies11132526.…”

“…A total of 167 lipid related genes which included genes associated blood lipids and bile acid metabolism were chosen by a previously reported gene capture strategy using a GenCap Custom Enrichment Kit (MyGenostics, Beijing, China)1028. The targeted region included all 3386 exons of all 167 lipid-related genes and was enriched with custom-made oligonucleotide probes.…”

“…In recent years, next-generation sequencing has also been successfully used to conduct screens for FH-causing mutations89. We previously showed that target exome sequencing (TES) successfully detected LDLR mutations in a FH patient10. The aim of the present study is to compare the TES technique with the DNA resequencing array technique in the genetic diagnosis of young patients with severe hypercholesterolemia.…”