Autosomal Recessive Hypercholesterolemia: Long-Term Cardiovascular Outcomes.

BACKGROUND: Autosomal recessive hypercholesterolemia (ARH) is a rare lipid disorder characterized by premature atherosclerotic cardiovascular disease (ASCVD). There are sparse data for clinical management and cardiovascular outcomes in ARH. OBJECTIVES: Evaluation of changes in lipid management, achievement of low-density lipoprotein cholesterol (LDL-C) goals and cardiovascular outcomes in ARH. METHODS: Published ARH cases were identified by electronic search. All corresponding authors and physicians known to treat these patients were asked to provide follow-up information, using a standardized protocol. RESULTS: We collected data for 52 patients (28 females, 24 males; 31.1 ± 17.1 years of age; baseline LDL-C: 571.9 ± 171.7 mg/dl). During a mean follow-up of 14.1 ± 7.3 years, there was a significant increase in the use of high-intensity statin and ezetimibe in combination with lipoprotein apheresis; in 6 patients, lomitapide was also added. Mean LDL-C achieved at nadir was 164.0 ± 85.1 mg/dl (-69.6% from baseline), with a better response in patients taking lomitapide (-88.3%). Overall, 23.1% of ARH patients reached LDL-C of <100 mg/dl. During follow-up, 26.9% of patients had incident ASCVD, and 11.5% had a new diagnosis of aortic valve stenosis (absolute risk per year of 1.9% and 0.8%, respectively). No incident stroke was observed. Age (≥30 years) and the presence of coronary artery disease at diagnosis were the major predictors of incident ASCVD. CONCLUSIONS: Despite intensive treatment, LDL-C in ARH patients remains far from targets, and this translates into a poor long-term cardiovascular prognosis. Our data highlight the importance of an early diagnosis and treatment and confirm the fact that an effective treatment protocol for ARH is still lacking.

Autosomal recessive hypercholesterolemia in Spain.

BACKGROUND AND AIMS: Autosomal recessive hypercholesterolemia (ARH) is a very rare disease, caused by mutations in LDL protein receptor adaptor 1 (LDLRAP1). It is characterized by high levels of low-density lipoprotein cholesterol (LDL-C) and increased risk of premature cardiovascular disease. We aimed to characterize ARH in Spain. METHODS: Data were collected from the Dyslipidemia Registry of the Spanish Atherosclerosis Society. A literature search was performed up to June 2017, and all diagnostic genetic studies for familial hypercholesterolemia of Spain were reviewed. RESULTS: Seven patients with ARH were identified, 6 true homozygous and one compound heterozygous with a novel mutation: c.[863C>T];p.[Ser288Leu]. High genetic heterogeneity was found in this cohort. True homozygous subjects for LDLRAP1 have more severe phenotypes than the compound heterozygous patient, but similar to patients with homozygous familial hypercholesterolemia (HoFH). Cardiovascular disease was present in 14% of the ARH patients. LDL-C under treatment was above 185 mg/dl and the response to PCSK9 inhibitors was heterogeneous. Finally, the estimated prevalence in Spain is very low, with just 1 case per 6.5 million people. CONCLUSIONS: ARH is a very rare disease in Spain, showing high genetic heterogeneity, similarly high LDL-C concentrations, but lower incidence of ASCVD than HoFH.

Homozygous Familial Hypercholesterolemia in Spain: Prevalence and Phenotype-Genotype Relationship.

BACKGROUND: Homozygous familial hypercholesterolemia (HoFH) is a rare disease characterized by elevated plasma levels of low-density lipoprotein cholesterol (LDL-C) and extremely high risk of premature atherosclerotic cardiovascular disease. HoFH is caused by mutations in several genes, including LDL receptor (LDLR), apolipoprotein B (APOB), proprotein convertase subtilisin/kexin type 9 (PCSK9), and LDL protein receptor adaptor 1 (LDLRAP1). No epidemiological studies have assessed HoFH prevalence or the clinical and molecular characteristics of this condition. Here, we aimed to characterize HoFH in Spain. METHODS AND RESULTS: Data were collected from the Spanish Dyslipidemia Registry of the Spanish Atherosclerosis Society and from all molecular diagnoses performed for familial hypercholesterolemia in Spain between 1996 and 2015 (n=16 751). Clinical data included baseline lipid levels and atherosclerotic cardiovascular disease events. A total of 97 subjects were identified as having HoFH-of whom, 47 were true homozygous (1 for APOB, 5 for LDLRAP1, and 41 for LDLR), 45 compound heterozygous for LDLR, 3 double heterozygous for LDLR and PSCK9, and 2 double heterozygous for LDLR and APOB. No PSCK9 homozygous cases were identified. Two variants in LDLR were identified in 4.8% of the molecular studies. Over 50% of patients did not meet the classical HoFH diagnosis criteria. The estimated HoFH prevalence was 1:450 000. Compared with compound heterozygous cases, true homozygous cases showed more aggressive phenotypes with higher LDL-C and more atherosclerotic cardiovascular disease events. CONCLUSIONS: HoFH frequency in Spain was higher than expected. Clinical criteria would underestimate the actual prevalence of individuals with genetic HoFH, highlighting the importance of genetic analysis to improve familial hypercholesterolemia diagnosis accuracy.

The influence of lipoprotein lipase gene variation on postprandial lipoprotein metabolism.

Lipoprotein lipase (LPL) is one of the key enzymes in the metabolism of triacylglycerol-rich lipoproteins (TRL). We evaluated whether the association of LPL HindIII (H1/H2) and Serine447-Stop (S447X) polymorphisms may explain the interindividual variability observed during postprandial lipemia. Fifty-one healthy male volunteers (26 with the H2S447 genotype, 15 with the H1X447 genotype, and 10 with the H1S447 genotype) were subjected to a vitamin A-fat load test consisting of 1 g fat/kg body weight and 60,000 IU vitamin A. Blood was drawn every hour until the 6th hour and every 2 h and 30 min until the 11th hour. Data revealed that subjects that are homozygous for the H2 allele (H2H2) showed a higher postprandial response for small TRL, retinyl palmitate (RP), large TRL-RP, large TRL-B48, and small TRL-B48 levels. Furthermore, in the case of the S447X polymorphism, 447Ter carriers had a lower postprandial response for small TRL-RP, large TRL-B48, and small TRL-RP. Subjects with the LPL H2S447 genotype had higher plasma triacylglycerol, large TRL-triacylglycerol, large TRL-RP, small TRL-RP, and large TRL-B48 (P < 0.037) than H1X447 subjects. The modifications observed in postprandial lipoprotein metabolism in young normolipemic males with LPL polymorphism could be involved in the lower risk of coronary artery disease associated with the H1X447 genotype.