Risk of cardiovascular disease with lipoprotein(a) in familial hypercholesterolemia: a review

Familial Hypercholesterolemia and Lipoprotein(a): A Gordian Knot in Cardiovascular Prevention

Familial hypercholesterolemia (FH) is the most frequent genetic disorder resulting in increased low-density lipoprotein cholesterol (LDL-C) levels from childhood, leading to premature atherosclerotic cardiovascular disease (ASCVD) if left untreated. FH diagnosis is based on clinical criteria and/or genetic testing and its prevalence is estimated as being up to 1:300,000−400,000 for the homozygous and ~1:200−300 for the heterozygous form. Apart from its late diagnosis, FH is also undertreated, despite the available lipid-lowering therapies. In addition, elevated lipoprotein(a) (Lp(a)) (>50 mg/dL; 120 nmol/L), mostly genetically determined, has been identified as an important cardiovascular risk factor with prevalence rate of ~20% in the general population. Novel Lp(a)-lowering therapies have been recently developed and their cardiovascular efficacy is currently investigated. Although a considerable proportion of FH patients is also diagnosed with high Lp(a) levels, there is a debate whether these two entities are associated. Nevertheless, Lp(a), particularly among patients with FH, has been established as a significant cardiovascular risk factor. In this narrative review, we present up-to-date evidence on the pathophysiology, diagnosis, and treatment of both FH and elevated Lp(a) with a special focus on their association and joint effect on ASCVD risk.

Relation of Serum Lipoprotein(a) Levels to Lipoprotein and Apolipoprotein Profiles and Atherosclerotic Diseases in Japanese Patients with Heterozygous Familial Hypercholesterolemia: Familial Hypercholesterolemia Expert Forum (FAME) Study

AIMS

Lipoprotein(a) [Lp(a)] is a plasma lipoprotein consisting of a low-density lipoprotein (LDL)-like particle with apolipoprotein (Apo)(a), attached via a disulfide bond to Apo B100. Previous studies have shown that high Lp(a) levels are associated with an increased risk of cardiovascular disease in patients with familial hypercholesterolemia (FH). To date, limited data are available as to distribution of Lp(a) in FH and associations of Lp(a) with other lipid profiles and cardiovascular disease. Our study aimed to investigate serum Lp(a) levels in relation to other lipid profiles and clinical conditions in the national largest-ever cohort of Japanese FH patients.

METHODS

This study is a secondary analysis of the Familial Hypercholesterolemia Expert Forum (FAME) Study that includes a Japanese nationwide cohort of FH patients. In 399 patients under treatment for heterozygous FH who had a baseline measurement of serum Lp(a), the present study examined the distribution of Lp(a) levels and associations of Lp(a) with other lipid profiles and clinical conditions including coronary artery disease (CAD).

RESULTS

The distribution of Lp(a) was skewed to the right with a median of 20.8 mg/dL, showing a log-normal distribution. Serum Apo B and Apo E levels were positively associated with Lp(a) levels. Age-adjusted mean of Apo B was 8.77 mg/dL higher and that of Apo E was 0.39 mg/dL higher in the highest category (40+ mg/dL) of Lp(a) than in the lowest category (＜20 mg/dL). LDL-C levels did not show such an association with Lp(a) levels. A tendency towards a positive relationship between Lp(a) and prevalent CAD was observed in men.

CONCLUSION

Our study demonstrated a distribution pattern of Lp(a) in Japanese FH patients and positive relationships of Lp(a) with Apo B and Apo E levels.

Clinical Aspects of Genetic and Non-Genetic Cardiovascular Risk Factors in Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is the most common monogenic metabolic disorder characterized by considerably elevated low-density lipoprotein cholesterol (LDL-C) levels leading to enhanced atherogenesis, early cardiovascular disease (CVD), and premature death. However, the wide phenotypic heterogeneity in FH makes the cardiovascular risk prediction challenging in clinical practice to determine optimal therapeutic strategy. Beyond the lifetime LDL-C vascular accumulation, other genetic and non-genetic risk factors might exacerbate CVD development. Besides the most frequent variants of three genes (LDL-R, APOB, and PCSK9) in some proband variants of other genes implicated in lipid metabolism and atherogenesis are responsible for FH phenotype. Furthermore, non-genetic factors, including traditional cardiovascular risk factors, metabolic and endocrine disorders might also worsen risk profile. Although some were extensively studied previously, others, such as common endocrine disorders including thyroid disorders or polycystic ovary syndrome are not widely evaluated in FH. In this review, we summarize the most important genetic and non-genetic factors that might affect the risk prediction and therapeutic strategy in FH through the eyes of clinicians focusing on disorders that might not be in the center of FH research. The review highlights the complexity of FH care and the need of an interdisciplinary attitude to find the best therapeutic approach in FH patients.

Familial Hypercholesterolemia and Lipoprotein(a): Two Partners in Crime?

PURPOSE OF REVIEW

Familial hypercholesterolemia is a high cardiovascular risk disorder. We will review the role of lipoprotein(a) in cardiovascular risk and in aortic valve stenosis in familial hypercholesterolemia, as well as its association with their phenotype, and strategies to identify this high-risk population.

RECENT FINDINGS

Patients with familial hypercholesterolemia have higher lipoprotein(a) levels mainly due to an increased frequency of LPA variants, and the cardiovascular risk is increased twofolds when both conditions coexist. Also, an increased risk for aortic valve stenosis and valve replacement has been observed with high lipoprotein(a) levels. Assessment of lipoprotein(a) during the cascade screening for familial hypercholesterolemia is a good opportunity to identify this high-risk population. High cardiovascular risk in familial hypercholesterolemia is increased even more when lipoprotein(a) is also elevated. Measurement of lipoprotein(a) in these patients is crucial to identify those subjects who need to intensify LDL-cholesterol reduction pending availability of lipoprotein(a)-specific treatments.

Therapeutic RNA-silencing oligonucleotides in metabolic diseases

Recent years have seen unprecedented activity in the development of RNA-silencing oligonucleotide therapeutics for metabolic diseases. Improved oligonucleotide design and optimization of synthetic nucleic acid chemistry, in combination with the development of highly selective and efficient conjugate delivery technology platforms, have established and validated oligonucleotides as a new class of drugs. To date, there are five marketed oligonucleotide therapies, with many more in clinical studies, for both rare and common liver-driven metabolic diseases. Here, we provide an overview of recent developments in the field of oligonucleotide therapeutics in metabolism, review past and current clinical trials, and discuss ongoing challenges and possible future developments.

Lipoprotein(a) and Familial Hypercholesterolemia: A Short Review Including the Laboratory Viewpoint

Lipoprotein(a) (Lp(a)) and low-density lipoprotein cholesterol (LDL-C) are risk factors for cardiovascular disease (CVD). Individuals with familial hypercholesterolemia (FH) have a risk for CVD due to a high LDL-C value. Lp(a) also increases the CVD risk in FH individuals; thus, the Lp(a) value should be carefully managed. The LDL-C value may partly include Lp(a)-cholesterol (Lp(a)-C) in the measurement. Based on the LDL-C value, some individuals are likely misclassified as having FH and/or the status of treatment of FH can be monitored. The present review describes about Lp(a) in FH individuals in terms of the measurement issue of Lp(a) and the related management of FH.