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

Abstract

Familial hypercholesterolemia (FH) is an autosomal dominant disorder. Although genetic testing is an important tool for detecting FH-causing mutations in patients, diagnostic methods for young patients with severe hypercholesterolemia are understudied. This study compares the target exome sequencing (TES) technique with the DNA resequencing array technique on young patients with severe hypercholesterolemia. A total of 20 unrelated patients (mean age 14.8 years) with total cholesterol > 10 mmol/L were included. 12 patient samples were processed by DNA resequencing array, 14 patient samples were processed by TES, and 6 patient samples were processed by both methods. Functional characterization of novel mutations was performed by flow cytometry. The mutation detection rate (MDR) of DNA resequencing array was 75%, while the MDR of TES was 100%. A total of 27 different mutations in the LDLR were identified, including 3 novel mutations and 8 mutations with previously unknown pathogenicity. Functional characterization of c.673delA, c.1363delC, p.Leu575Phe and p.Leu582Phe variants found that all of them are pathogenic. Additionally, 7 patients were diagnosed with Heterozygous FH (HeFH) in which lipid levels were significantly higher than common HeFH patients. This data indicates that TES is a very efficient tool for genetic diagnosis in young patients with severe hypercholesterolemia.

Predicted pathogenic mutations in STAP1 are not associated with clinically defined familial hypercholesterolemia

“…For example, Futema et al [32] sequenced the exome of 125 and PCSK9 genes, not reporting any variant in STAP1 gene. Jiang et al [35] used targeted exome sequencing in young patients with severe hypercholesterolemia and they discover 27 mutations in LDLR, including 3 novel mutations in LDLR gene. Iacocca et al [36] used targeted next-generation sequencing to discover copy number variations in APOB, PCSK9, LDLRAP1, APOE, STAP1, LIPA, and ABCG5/8 genes.…”

Functional Characterization of p.(Arg160Gln) PCSK9 Variant Accidentally Found in a Hypercholesterolemic Subject

“…Heterozygous Familial Hypercholesterolemia is the most common genetic disease, which requires early detection and appropriate treatment to reduce cardiovascular events [ 1 ]. In recent years, and thanks to massive sequencing of DNA, many variants of genes involved in the development of FH have been identified; however, not all of them are pathogenic [ 1 , 9 , 16 , 17 ]. Although genetic analyses constitute an important step for diagnosis, establishing the pathogenicity of these variants through functional studies is essential to make an accurate diagnosis [ 18 ].…”

Expanding the genetic spectrum for Chinese familial hypercholesterolemia population with six genetic mutations identified using a next‐generation sequencing‐based laboratory‐developed screening test

“…C.G1879A (p.A627T) and c.G682T (p.E228X) are two common variants that have been reported by a number of studies in China, including Taiwan (Cao et al, 2018 ; Chang, 2003 ; Du et al, 2016 ; Jiang, Sun, et al, 2016 ; Jiang, Wu, et al, 2016 ; Mak et al, 1998 ). Furthermore, c.G682T has also been reported in other Asian countries, such as Korea (Han et al, 2015 ), Russia (Zakharova et al, 2005 ), and others (Reiman et al, 2016 ).…”