Targeted sequencing in patients with clinically diagnosed hereditary lipid metabolism disorder and acute coronary syndrome

Abstract

The actual prevalence of genetic variants causing familial hypercholesterolemia (FH) in every population remains unknown. The aim of this work was to determine the spectrum of pathogenic variants in patients with acute coronary syndrome (ACS) and clinically diagnosed FH using targeted sequencing. We selected 38 patients with ACS from the sample of 2,081 participants of two multicenter observational studies (2004–2007; 2014–2016) who had a clinical diagnosis of FH based on the Dutch Lipid Clinic Network score and Simon Broome criteria. The men and women included in the study were ≤ 55 and ≤ 60 years of age, respectively. Molecular genetic screening was done by targeted next-generation sequencing. We started by sequencing 3 genes associated with FH, including LDLR, APOB, and PCSK9. If no relevant variants were detected, the panel was expanded. Of 38 patients, 24 (63.2%) were shown to have mutations that could cause clinical manifestations of FH and premature coronary artery disease. All patients were heterozygous carriers. Mutations were detected in three “classic” genes LDLR, APOB, and PCSK9 associated with FH, as well as in other genes involved in lipid metabolism, such as APOE, ABCA1, ABCG5, ABCG8, LPL, ANGPTL3, and MTTP. Five variants detected in our study sample had not been described previously: the pathogenic p.Val273_Cys313del variant of the LDLR gene, the likely pathogenic p.Arg160His variant in the APOE gene, two variants of uncertain significance p.Glu612Lys and c.*415G>A in the PCSK9 gene, and the mutant variant p.Ala776Ser in the LDLR gene. We conclude that the use of clinical diagnostic criteria in patients with ACS and FH enables identification of carriers of both “classic” mutations associated with FH and rare genetic variants that can be phenotypically expressed as FH.

Familial Hypercholesterolemia in Russia: Three Decades of Genetic Studies

“…This result is at variance with data from previous studies conducted in Russia and elsewhere in the world, showing that patients with LDLR mutations constitute the great majority (usually 70-80%) of cases with a hereditary background (Defesche et al, 2017). This discrepancy likely arose from the distinctive method of sampling and inaccuracy of the clinical FH diagnosis, making the results obtained (Averkova et al, 2018) incomparable with earlier data (Meshkov et al, 2009).…”

“…New expectations of more efficient DNA-based diagnosis of FH have been raised by the introduction of targeted sequencing in routine practice. A recent study of 38 patients from Moscow with clinically diagnosed FH and acute coronary syndrome revealed genetic abnormalities in 24 individuals (63.2%) (Averkova et al, 2018); however, mutations in LDLR were found in only 10% of probands (four sequence variants, of which one (c.58G > A p.Gly20Arg) was experimentally demonstrated to be neutral). This result is at variance with data from previous studies conducted in Russia and elsewhere in the world, showing that patients with LDLR mutations constitute the great majority (usually 70-80%) of cases with a hereditary background (Defesche et al, 2017).…”

“…A second large deletion in LDLR was identified in the Russian population by geneticists in Moscow after the introduction of targeted sequencing (Averkova et al, 2018). As Southern blot hybridization is a time-consuming and relatively inefficient method for mutation screening, no more attempts to use this approach to identify large-scale rearrangements at the LDLR locus have been undertaken in Russia.…”

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 ).…”