Ascertainment Bias in the Association Between Elevated Lipoprotein(a) and Familial Hypercholesterolemia.

BACKGROUND: Lipoprotein(a) is an atherogenic low-density lipoprotein-like particle and circulating levels are largely determined by genetics. Patients with familial hypercholesterolemia (FH) have elevated lipoprotein(a); however, it remains unclear why. OBJECTIVES: This study compared the levels of lipoprotein(a) and associated genetic factors between individuals that were ascertained for FH clinically versus genetically. METHODS: We investigated causes of elevated lipoprotein(a) in individuals with clinically diagnosed FH (FH cohort, n = 391) and in individuals with genetically diagnosed FH from the general population (UK Biobank; n = 37,486). RESULTS: Patients in the FH cohort had significantly greater lipoprotein(a) levels than either the general population or non-FH dyslipidemic patients. This was accounted for by increased frequency of the rs10455872-G LPA risk allele (15.1% vs. 8.8%; p < 0.05). However, within the FH cohort, lipoprotein(a) levels did not differ based on the presence or absence of an FH-causing variant (means = 1.43 log mg/dl vs. 1.42 log mg/dl; p = 0.97). Lipoprotein(a) levels were also not statistically different between individuals with and without an FH-causing variant in the UK Biobank cohort, which represents a population sample not biased to cardiovascular ascertainment (n = 221 vs. 37,486). We performed a phenome-wide association study between LPA genotypes and 19,202 phenotypes to demonstrate that elevated lipoprotein(a) is associated with increased low-density lipoprotein cholesterol, a family history of cardiovascular disease, premature coronary artery disease, and a diagnosis of FH. CONCLUSIONS: These results suggest that FH does not cause elevated lipoprotein(a), but that elevated lipoprotein(a) increases the likelihood that an individual with genetic FH will be clinically recognized.

Risk of Premature Atherosclerotic Disease in Patients With Monogenic Versus Polygenic Familial Hypercholesterolemia.

BACKGROUND: A pathogenic variant in LDLR, APOB, or PCSK9 can be identified in 30% to 80% of patients with clinically-diagnosed familial hypercholesterolemia (FH). Alternatively, ∼20% of clinical FH is thought to have a polygenic cause. The cardiovascular disease (CVD) risk associated with polygenic versus monogenic FH is unclear. OBJECTIVES: This study evaluated the effect of monogenic and polygenic causes of FH on premature (age <55 years) CVD events in patients with clinically diagnosed FH. METHODS: Targeted sequencing of genes known to cause FH as well as common genetic variants was performed to calculate polygenic scores in patients with "possible," "probable," or "definite" FH, according to Dutch Lipid Clinic Network Criteria (n = 626). Patients with a polygenic score ≥80th percentile were considered to have polygenic FH. We examined the risk of unstable angina, myocardial infarction, coronary revascularization, or stoke. RESULTS: A monogenic cause of FH was associated with significantly greater risk of CVD (adjusted hazard ratio: 1.96; 95% confidence interval: 1.24 to 3.12; p = 0.004), whereas the risk of CVD in patients with polygenic FH was not significantly different compared with patients in whom no genetic cause of FH was identified. However, the presence of an elevated low-density lipoprotein cholesterol (LDL-C) polygenic risk score further increased CVD risk in patients with monogenic FH (adjusted hazard ratio: 3.06; 95% confidence interval: 1.56 to 5.99; p = 0.001). CONCLUSIONS: Patients with monogenic FH and superimposed elevated LDL-C polygenic risk scores have the greatest risk of premature CVD. Genetic testing for FH provides important prognostic information that is independent of LDL-C levels.

Familial hypercholesterolaemia patient support groups and advocacy: A multinational perspective.

Familial hypercholesterolaemia (FH) is an autosomal-dominant disorder associated with high low-density lipoprotein cholesterol (LDL-C). Left untreated, 50% of men with FH will develop coronary heart disease by the age of 50 and 30% of women by the age 60 [1,2]. It is estimated that the prevalence may be as high as one in 250 people, with most undiagnosed. This article explores the development of advocacy in FH patient organisations, citing examples from Canada, the Netherlands, Spain, the US and the UK as well as the pan-European patient organisation, FH Europe. The article demonstrates that for patient advocacy, the link with medical and scientific expertise is essential to ensure that advocacy for familial hypercholesterolaemia is well-founded and credible and that patient associations are prepared to take a long-term view on achieving improvements in identification and treatment.

Consumption of a dietary portfolio of cholesterol lowering foods improves blood lipids without affecting concentrations of fat soluble compounds.

BACKGROUND: Consumption of a cholesterol lowering dietary portfolio including plant sterols (PS), viscous fibre, soy proteins and nuts for 6 months improves blood lipid profile. Plant sterols reduce blood cholesterol by inhibiting intestinal cholesterol absorption and concerns have been raised whether PS consumption reduces fat soluble vitamin absorption. OBJECTIVE: The objective was to determine effects of consumption of a cholesterol lowering dietary portfolio on circulating concentrations of PS and fat soluble vitamins. METHODS: Using a parallel design study, 351 hyperlipidemic participants from 4 centres across Canada were randomized to 1 of 3 groups. Participants followed dietary advice with control or portfolio diet. Participants on routine and intensive portfolio involved 2 and 7 clinic visits, respectively, over 6 months. RESULTS: No changes in plasma concentrations of α and γ tocopherol, lutein, lycopene and retinol, but decreased ß-carotene concentrations were observed with intensive (week 12: p = 0.045; week 24: p = 0.039) and routine (week 12: p = 0.031; week 24: p = 0.078) portfolio groups compared to control. However, cholesterol adjusted ß-carotene and fat soluble compound concentrations were not different compared to control. Plasma PS concentrations were increased with intensive (campesterol:p = 0.012; ß-sitosterol:p = 0.035) and routine (campesterol: p = 0.034; ß-sitosterol: p = 0.080) portfolio groups compared to control. Plasma cholesterol-adjusted campesterol and ß-sitosterol concentrations were negatively correlated (p < 0.001) with total and LDL-C levels. CONCLUSION: Results demonstrate that consuming a portfolio diet reduces serum total and LDL-C levels while increasing PS values, without altering fat soluble compounds concentrations. The extent of increments of PS with the current study are not deleterious and also maintaining optimum levels of fat soluble vitamins are of paramount necessity to maintain overall metabolism and health. Results indicate portfolio diet as one of the best options for CVD risk reduction. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00438425.

Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.

CONTEXT: Combining foods with recognized cholesterol-lowering properties (dietary portfolio) has proven highly effective in lowering serum cholesterol under metabolically controlled conditions. OBJECTIVE: To assess the effect of a dietary portfolio administered at 2 levels of intensity on percentage change in low-density lipoprotein cholesterol (LDL-C) among participants following self-selected diets. DESIGN, SETTING, AND PARTICIPANTS: A parallel-design study of 351 participants with hyperlipidemia from 4 participating academic centers across Canada (Quebec City, Toronto, Winnipeg, and Vancouver) randomized between June 25, 2007, and February 19, 2009, to 1 of 3 treatments lasting 6 months. INTERVENTION: Participants received dietary advice for 6 months on either a low-saturated fat therapeutic diet (control) or a dietary portfolio, for which counseling was delivered at different frequencies, that emphasized dietary incorporation of plant sterols, soy protein, viscous fibers, and nuts. Routine dietary portfolio involved 2 clinic visits over 6 months and intensive dietary portfolio involved 7 clinic visits over 6 months. MAIN OUTCOME MEASURES: Percentage change in serum LDL-C. RESULTS: In the modified intention-to-treat analysis of 345 participants, the overall attrition rate was not significantly different between treatments (18% for intensive dietary portfolio, 23% for routine dietary portfolio, and 26% for control; Fisher exact test, P = .33). The LDL-C reductions from an overall mean of 171 mg/dL (95% confidence interval [CI], 168-174 mg/dL) were -13.8% (95% CI, -17.2% to -10.3%; P < .001) or -26 mg/dL (95% CI, -31 to -21 mg/dL; P < .001) for the intensive dietary portfolio; -13.1% (95% CI, -16.7% to -9.5%; P < .001) or -24 mg/dL (95% CI, -30 to -19 mg/dL; P < .001) for the routine dietary portfolio; and -3.0% (95% CI, -6.1% to 0.1%; P = .06) or -8 mg/dL (95% CI, -13 to -3 mg/dL; P = .002) for the control diet. Percentage LDL-C reductions for each dietary portfolio were significantly more than the control diet (P < .001, respectively). The 2 dietary portfolio interventions did not differ significantly (P = .66). Among participants randomized to one of the dietary portfolio interventions, percentage reduction in LDL-C on the dietary portfolio was associated with dietary adherence (r = -0.34, n = 157, P < .001). CONCLUSION: Use of a dietary portfolio compared with the low-saturated fat dietary advice resulted in greater LDL-C lowering during 6 months of follow-up. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00438425.