Lipoprotein(a) Genotype Influences the Clinical Diagnosis of Familial Hypercholesterolemia

Genetic heterogeneity of familial hypercholesterolaemia in two populations from two different countries

BACKGROUND

Familial hypercholesterolemia (FH) is a genetically determined monogenic disorder of predominantly autosomal dominant inheritance. A number of studies on differences in the genetic profile of patients with FH have demonstrated the importance of a more substantive evaluation of genetic features. The aim of this study was to evaluate the genetic profile of patients with clinical FH among Italian and Russian patients.

METHODS

We included 144 Italian and 79 Russian FH patients; clinical diagnosis was based on the same criteria. Patients were divided in: positive to genetic test (one causative variant), inconclusive (only variants of uncertain clinical significance [VUS]), and negative (with likely benign/benign variants, heterozygous variants in LDLRAP1 gene, or without causative variants).

RESULTS

The genetic test was positive in 76.4 % of the Italian patients and in 49.4 % of the Russian patients. The presence of VUS alone was detected in 7.6 % and in 19.0 % (p < 0.001), respectively. Among patients with positive genetic diagnosis, pre-treatment LDL-C levels were higher in the Russian cohort (353.5 ± 111.3 vs. 302.7 ± 52.1 mg/dL, p = 0.009), as well as the percentage of treated patients (53.8 % vs. 14.5 %, p < 0.001) and the prevalence of premature coronary heart disease (12.8 % vs. 3.6 %, p = 0.039). Among patients carrying only VUS, mean pre-treatment LDL-C levels were similar between the cohorts (299.5 ± 68.1 vs. 295.3 ± 46.8 mg/dL, p = 0.863). Among pathogenic/likely pathogenic variants and VUS, only 5 % and 4 % was shared between the two cohorts, respectively.

CONCLUSION

The genetic background of patients clinically diagnosed with FH in two different countries is characterized by high variability.

Impact of 12-SNP and 6-SNP Polygenic Scores on Predisposition to High LDL-Cholesterol Levels in Patients with Familial Hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) comprises high LDL-cholesterol (LDL-c) levels and high cardiovascular disease risk. In the absence of pathogenic variants in causative genes, a polygenic basis was hypothesized.

METHODS

In a population of 418 patients (excluding homozygotes) with clinical suspicion of FH, the FH-causative genes and the regions of single nucleotide polymorphisms (SNPs) included in 12-SNP and 6-SNP scores were sequenced by next-generation sequencing, allowing for the detection of pathogenic variants (V+) in 220 patients. To make a comparison, only patients without uncertain significance variants (V-/USV-) were considered (n = 162).

RESULTS

Higher values of both scores were observed in V+ than in V-. Considering a cut-off leading to 80% of V-/USV- as score-positive, a lower prevalence of patients positive for both 12-SNP and 6-SNP scores was observed in V+ (p = 0.010 and 0.033, respectively). Mainly for the 12-SNP score, among V+ patients, higher LDL-c levels were observed in score-positive (223 mg/dL -IQR 187-279) than in negative patients (212 mg/dL -IQR 162-240; p = 0.006). Multivariate analysis confirmed the association of scores and LDL-c levels independently of age, sex, and presence of pathogenic variants and revealed a greater association in children.

CONCLUSIONS

The 12-SNP and 6-SNP polygenic scores could explain hypercholesterolemia in patients without pathogenic variants as well as the variability of LDL-c levels among patients with FH-causative variants.

Advances in familial hypercholesterolemia

Familial hypercholesterolemia (FH), a semi-dominant genetic disease affecting more than 25 million people worldwide, is associated with severe hypercholesterolemia and premature atherosclerotic cardiovascular disease. Over the last decade, advances in data analysis, screening, diagnosis and cardiovascular risk stratification has significantly improved our ability to deliver precision medicine for these patients. Furthermore, recent updates on guideline recommendations and new therapeutic approaches have also proven to be highly beneficial. It is anticipated that both ongoing and upcoming clinical trials will offer further insights for the care and treatment of FH patients.

Measuring lipoprotein(a) for cardiovascular disease prevention - in whom and when?

PURPOSE OF REVIEW

The aim of this study is to summarize major cardiovascular guideline recommendations on lipoprotein(a) and highlighting recent findings that emphasize how measuring lipoprotein(a) once in all adults is meaningful regardless of age, sex, comorbidities, or ethnicity.

RECENT FINDINGS

Many international guidelines now recommend once in a lifetime measurement of lipoprotein(a) in all adult individuals to facilitate accurate risk prediction. Lipoprotein(a)-lowering therapy to reduce cardiovascular disease is on the horizon, with results from the first phase 3 trial expected in 2025.

SUMMARY

Elevated lipoprotein(a) is an independent causal risk factor for atherosclerotic cardiovascular disease and aortic valve stenosis and measuring lipoprotein(a) once in all individuals regardless of age, sex, comorbidities, or ethnicity is meaningful to aid in risk stratification.

Evidence and Uncertainties on Lipoprotein(a) as a Marker of Cardiovascular Health Risk in Children and Adolescents

Lipoprotein(a) (Lp(a)) is made up of apoprotein(a) (apo(a)) and an LDL-like particle. The LPA gene encodes apo(a) and thus determines the characteristics and amount of apo(a) and Lp(a). The proportion of Lp(a) in each individual is genetically determined and is only minimally modifiable by the environment or diet. Lp(a) has important pro-atherosclerotic and pro-inflammatory effects. It has been hypothesized that Lp(a) also has pro-coagulant and antifibrinolytic actions. For these reasons, high Lp(a) values are an important independent risk factor for cardiovascular disease and calcific aortic valve stenosis. Numerous studies have been performed in adults about the pathophysiology and epidemiology of Lp(a) and research is under way for the development of drugs capable of reducing Lp(a) plasma values. Much less information is available regarding Lp(a) in children and adolescents. The present article reviews the evidence on this topic. The review addresses the issues of Lp(a) changes during growth, the correlation between Lp(a) values in children and those in their parents, and between Lp(a) levels in children, and the presence of cardiovascular disease in the family. Gaining information on these points is particularly important for deciding whether Lp(a) assay may be useful for defining the cardiovascular risk in children, in order to plan a prevention program early.