The Clinical Genome Resource (ClinGen) Familial Hypercholesterolemia Variant Curation Expert Panel consensus guidelines for LDLR variant classification

PURPOSE: In 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published consensus standardized guidelines for sequence-level variant classification in Mendelian disorders. To increase accuracy and consistency, the Clinical Genome Resource Familial Hypercholesterolemia (FH) Variant Curation Expert Panel was tasked with optimizing the existing ACMG/AMP framework for disease-specific classification in FH. In this study, we provide consensus recommendations for the most common FH-associated gene, LDLR, where >2300 unique FH-associated variants have been identified. METHODS: The multidisciplinary FH Variant Curation Expert Panel met in person and through frequent emails and conference calls to develop LDLR-specific modifications of ACMG/AMP guidelines. Through iteration, pilot testing, debate, and commentary, consensus among experts was reached. RESULTS: The consensus LDLR variant modifications to existing ACMG/AMP guidelines include (1) alteration of population frequency thresholds, (2) delineation of loss-of-function variant types, (3) functional study criteria specifications, (4) cosegregation criteria specifications, and (5) specific use and thresholds for in silico prediction tools, among others. CONCLUSION: Establishment of these guidelines as the new standard in the clinical laboratory setting will result in a more evidence-based, harmonized method for LDLR variant classification worldwide, thereby improving the care of patients with FH

Heterozygous familial hypercholesterolaemia in specialist centres in South Africa, Australia and Brazil: Importance of early detection and lifestyle advice

Background and aims: Familial hypercholesterolaemia (FH) is the commonest monogenic disorder that accelerates atherosclerotic cardiovascular disease. We compared and contrasted the characteristics of patients from three specialist centres in the southern hemisphere. Methods: Adult index-cases with molecularly diagnosed heterozygous FH attending specialist lipid centres in Cape Town, Perth and São Paulo were studied. Myocardial infarction, revascularisation, hypertension, diabetes, smoking and lipid-lowering treatment were recorded at the time of diagnosis and compared across the three centres. Results: The spectrum of genetic variants causative of FH was significantly different in patients attending the centres in South Africa compared with Australia and Brazil. Hypertension and diabetes were more prevalent in Brazilian and Australian patients, than in South African patients, but the frequency of smoking was significantly greater in South Africa than the other two centres (p<0.01). Age, male sex and smoking were significant independent predictors of coronary artery disease (CAD) in all three countries (p<0.05). Conclusions: Patients with FH in three specialist centres in the southern hemisphere exhibit a high prevalence of non-cholesterol cardiovascular disease risk factors. Older age, male sex and smoking were more common among subjects with CAD. In all three countries, there should be vigorous programmes for the control of risk factors beyond good control of hypercholesterolaemia among patients with FH. Promotion of a healthy lifestyle, especially anti-smoking advice, is of paramount importance

Association of dietary components with dyslipidemia and low-grade inflammation biomarkers in adults with heterozygous familial hypercholesterolemia from different countries

The association of components of a low saturated fat (SFA) and of a Mediterranean diet was tested with atherosclerosis biomarkers in 190 familial hypercholesterolemia adults (FH) from Brazil (BR) and Spain (SP). Median blood LDL-C, Apolipoprotein B (apoB), and C reactive protein (hs-CRP) concentrations were higher in BR than in SP: 179.0 vs.161 mg/dL; 141 vs. 103 mg/dL; and 1.6 vs. 0.8 mg/L respectively (all p < 0.001). In BR there was lower median total fat (22.3 vs. 38.3%) and SFA (8.1 vs. 12.5%) but higher cholesterol (283.3 mg vs.188.9 mg) and carbohydrate (57.1 vs. 42.5%) consumption (all p < 0.001). Inverse associations were encountered between fibers, mono, and polyunsaturated fats and their ratios to SFA with LDL-C and ApoB (all p < 0.001). There was a direct association respectively of cholesterol with lipid biomarkers and of carbohydrates and trans-fatty acids with hs-CRP while other fats showed inverse relations with the latter (p < 0.001).The funding of Sociedade Hospital Samaritano and Ministério da Saúde (PROADI-SUS; SIPAR: 25000.180.672/2011-81) and FAPESP (grant no 2013/17368-0) are gratefully acknowledged

ClinVar database of global familial hypercholesterolemia-associated DNA variants

Accurate and consistent variant classification is imperative for incorporation of rapidly developing sequencing technologies into genomic medicine for improved patient care. An essential requirement for achieving standardized and reliable variant interpretation is data sharing, facilitated by a centralized open‐source database. Familial hypercholesterolemia (FH) is an exemplar of the utility of such a resource: it has a high incidence, a favorable prognosis with early intervention and treatment, and cascade screening can be offered to families if a causative variant is identified. ClinVar, an NCBI‐funded resource, has become the primary repository for clinically relevant variants in Mendelian disease, including FH. Here, we present the concerted efforts made by the Clinical Genome Resource, through the FH Variant Curation Expert Panel and global FH community, to increase submission of FH‐associated variants into ClinVar. Variant‐level data was categorized by submitter, variant characteristics, classification method, and available supporting data. To further reform interpretation of FH‐associated variants, areas for improvement in variant submissions were identified; these include a need for more detailed submissions and submission of supporting variant‐level data, both retrospectively and prospectively. Collaborating to provide thorough, reliable evidence‐based variant interpretation will ultimately improve the care of FH patients