👤 Samuel D Maidman

The development of tendinous xanthomas in childhood with a low-density lipoprotein (LDL) cholesterol level >400 mg/dL is characteristic of homozygous familial hypercholesterolemia (FH). We present the case of a patient with a severely elevated LDL cholesterol level and childhood-onset xanthomas who fulfilled clinical criteria for homozygous FH. However, genetic and absorption testing clarified his phenotype to be a unique digenic overlap of both heterozygous FH and heterozygous sitosterolemia with marked elevations in cholesterol absorption indices. Treatment with ezetimibe 10 mg daily resulted in a dramatic reduction in LDL cholesterol. Sitosterolemia, a rare autosomal recessive disorder of plant sterol hyperabsorption, can also result in xanthomatosis and thus can mimic FH. Although it is usually a homozygous disease, heterozygotes may exhibit intermediary phenotypes. Patients with severe hypercholesterolemia should undergo genetic and biochemical profiling for diagnostic confirmation and for ensuring that they receive optimal, personalized therapy. Show less

Despite the modern era of effective and safe high-intensity statins and non-statin agents, a significant portion of patients are still unable to achieve guideline-recommended lipid goals for the prevention of atherosclerotic cardiovascular disease (ASCVD) events. Accordingly, novel strategies are needed to further mitigate residual risk for patients on the background of maximally tolerated lipid-lowering therapies. The past decade has seen an explosion of new agents leveraging ribonucleic acid (RNA)-based technology which reduce plasma lipoprotein levels. In this state-of-the-art review, we examine the ongoing clinical development of lipid-lowering RNA therapeutics. We discuss the efficacy and safety profiles of antisense oligonucleotides and small interfering RNA agents targeting low-density lipoprotein, lipoprotein(a), and triglyceride-rich lipoproteins. We also present challenges future clinical trials must answer to prove RNA therapeutics as a viable strategy for ASCVD prevention among patients with refractory hyperlipidemia. Show less

Multiple agents are being developed that inhibit apolipoprotein (apo) C-III. This state-of-the-art review examines their potential for atherosclerotic cardiovascular disease (ASCVD) risk reduction. Apo C-III, an apolipoprotein on the surface of triglyceride-rich lipoproteins (TRLs), impairs clearance of TRLs through both lipoprotein lipase dependent and independent pathways, thereby resulting in increased concentrations of triglycerides. Apo C-III has also been shown to have pro-atherogenic effects when bound to high-density lipoprotein (HDL) particles. Classical and genetic epidemiology studies provide support for the concept that apo C-III is associated with an increased risk of ASCVD events. Drug efficacy of agents that silence APOC3 mRNA has been studied in populations with varying hypertriglyceridemia severity, including those with familial chylomicronemia syndrome, multifactorial chylomicronemia syndrome/severe hypertriglyceridemia, and mixed hyperlipidemia. Randomized controlled trials have reported significant reductions in TG and non-HDL cholesterol levels among these patients treated with APOC3 inhibitors. Upcoming clinical outcomes trials seek to establish a role for APOC3 inhibitors to reduce risk of ASCVD. Show less