Verification of Underlying Genetic Cause in a Cohort of Russian Patients with Familial Hypercholesterolemia Using Targeted Next Generation Sequencing

Abstract

Russian patients with familial hypercholesterolemia (FH) were screened for pathogenic mutations using targeted next generation sequencing. Genetic testing was performed in 52 probands with definite or probable FH based on the Dutch lipid clinic network criteria (DLCN score ≥ 6). Blood samples were studied by massive parallel sequencing (Illumina HiSeq 1500 platform) using a custom capture library related to dyslipidemia and premature atherosclerosis. Mutations considered to be responsible for monogenic FH were identified in 48% of the probands: 24 with mutations in the LDLR gene and two with a mutation in the APOB gene. There were 22 pathogenic/likely pathogenic mutations in LDLR, eight of which have not been previously described in the literature. Four patients with a clinical picture of homozygous FH had two heterozygous LDLR mutations. Although mutation-negative patients had highly elevated total cholesterol and low-density lipoprotein cholesterol levels, only half of them had a family history of hypercholesterolemia. With respect to heterozygous FH, mutation-positive patients had higher maximum total cholesterol levels (p = 0.01), more severe carotid atherosclerotic lesions, and a higher percentage of premature peripheral artery disease (p = 0.03) than mutation-negative ones. However, the number of patients who suffered from myocardial infarction was similar between the two groups.

The LDLR, APOB, and PCSK9 Variants of Index Patients with Familial Hypercholesterolemia in Russia

“…Most of these variants were unique but some LDLR variants occurred in several unrelated patients: p.Cys68Phe, p.Pro196Arg, p.Cys318Trp, p.Tyr375Asp and p.Ile566Phe. Of 35 variants previously described in the literature [ 6 , 7 , 8 , 9 , 10 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ] only for the Russian population, six variants were also found in this study. Most of these variants were also unique, except for variant LDLR -p.Cys160Gly, that was found in six unrelated patients.…”

“…The search strategy described above yielded 665 citations; 474 remained after duplicate removal. After the analysis of the abstracts referring to genetic testing or LDLR , APOB and PCSK9 variants in FH patients, 27 articles were selected, of which 25 contained data on the LDLR , APOB , and PCSK9 variants, including three of previously published articles by our group [ 6 , 7 , 8 , 9 , 10 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. These articles describe 91 causal variants of LDLR gene, one variant of APOB, and one variant of PCSK9 ( Figure 1 , Table A1 , Table A2 and Table A3 in Appendix A ).…”

“…About 2900 variants in the LDLR , APOB and PCSK9 genes potentially associated with FH have been described by the members of the ClinGen FH Variant Curation Expert Panel from 13 different countries [ 5 ]. Nevertheless, the genetics of FH in a Russian population is still poorly understood, with only about 60 variants of LDLR and APOB genes described in single publications [ 6 , 7 , 8 , 9 , 10 ]. The aim of this study is to present data on the spectrum of the LDLR , APOB and PCSK9 gene variants in a cohort of 595 index Russian patients with FH, and to perform an additional systematic analysis of the literature for the period of 1995–2020 on LDLR , APOB and PCSK9 gene variants described in Russian FH patients.…”

Familial Hypercholesterolemia in Russia: Three Decades of Genetic Studies

“…When this review was ready for submission a report was published on a cohort of 52 probands with definite or probable diagnosis of FH according to DLCN criteria (Semenova et al, 2020). Targeted NGS was used to study that cohort consisting of individuals from various regions of Russia who had settled in Moscow.…”

Finding inhibitors for PCSK9 using computational methods

“…The risk of atherosclerotic cardiovascular disease (ASCVD) increases in patients, who already have mutations in FH genes such as LDLR , PCSK9 or ApoB , when compared to patients without any mutation, but with similar cholesterol levels [ 2 ]. Mutated FH related genes may lead to an increased level of LDL cholesterol (LDL-C) [ 3 ] leading to malfunction of the vascular endothelium.…”