Incorporation of genetic testing significantly increases the number of individuals diagnosed with familial hypercholesterolemia

Methylation status of LDLR, PCSK9 and LDLRAP1 is associated with cardiovascular events in familial hypercholesterolemia

Aim: Methylation of LDLR, PCSK9 and LDLRAP1 CpG sites was assessed in patients with familial hypercholesterolemia (FH). Methods: DNA methylation of was analyzed by pyrosequencing in 131 FH patients and 23 normolipidemic (NL) subjects.Results:  LDLR, PCSK9 and LDLRP1 methylation was similar between FH patients positive (MD) and negative (non-MD) for pathogenic variants in FH-related genes. LDLR and PCSK9 methylation was higher in MD and non-MD groups than NL subjects (p < 0.05). LDLR, PCSK9 and LDLRAP1 methylation profiles were associated with clinical manifestations and cardiovascular events in FH patients (p < 0.05).Conclusion: Differential methylation of LDLR, PCSK9 and LDLRAP1 is associated with hypercholesterolemia and cardiovascular events. This methylation profile maybe useful as a biomarker and contribute to the management of FH.

Expanded genetic testing in familial hypercholesterolemia-A single center's experience

Objective

Assess the yield of genetic testing for pathogenic variants in ABCG5, ABCG8, LIPA, and APOE in individuals with personal and family histories suggestive of familial hypercholesterolemia.

Methods

Retrospective review of patients seen in the Advanced Lipid Disorders Clinic at Johns Hopkins.

Results

In the lipid clinic at a single center during the years 2015-2023, 607 patients underwent genetic testing for familial hypercholesterolemia, of which 263 underwent the expanded genetic testing for sitosterolemia. Eighty-eight patients had genetic testing which included APOE, and 22 patients had testing which included LIPA. Among these, one patient was identified to have a pathogenic variant in APOE and another patient with a pathogenic variant in ABCG5 (0.7 % yield). The frequency of a positive result was double that of a variant of uncertain significance.

Conclusion

These data suggest in rare cases expanded testing can provide answers for patients and families with a minimal likelihood of a variant of uncertain significance.

Prevalence of genetically defined familial hypercholesterolemia and the impact on acute myocardial infarction in Taiwanese population: A hospital-based study

Background

Familial hypercholesterolemia (FH) is a common genetic disorder with markedly increased risk of coronary artery diseases (CAD), especially acute myocardial infarction (AMI). However, genetic tests for FH are not always necessary in the current diagnostic criteria of FH, which might lead to underestimation of the prevalence of FH and a lack of awareness of FH-associated CAD and AMI. We aimed to explore the prevalence of genetically defined FH in the hospital-based population and to determine the impact of FH risk variants on CAD and AMI.

Methods

The study participants were recruited between June 24, 2019 and May 12, 2021, at a medical center in Taiwan, in cooperation with the Taiwan Precision Medicine Initiative (TPMI) project. The prevalence of FH was calculated and the effects of FH pathogenic variants on CAD and AMI were analyzed by logistic regression models and shown as ORs and 95% CI.

Results

The prevalence of genetically defined FH was 1.13% in the hospital-based population in Taiwan. Highest LDL and total cholesterol levels were observed in patients with LDLR rs28942084 (LDL 219.4±55.2; total cholesterol 295.8±55.4). There was an approximately 4-fold increased risk of hyperlipidemia in subjects with the LDLR rs769446356 polymorphism (OR, 4.42; 95% CI, 1.92-10.19) and AMI in individuals with the LDLR rs730882109 polymorphism (OR, 3.79; 95% CI, 2.26-6.35), and a 2-fold increased risk of CAD in those with the LDLR rs749038326 polymorphism (OR, 2.14; 95% CI, 1.31-3.50), compared with the groups without pathogenic variants of FH.

Conclusions

The prevalence of genetically defined FH was 1.13% in the hospital-based population in Taiwan, which was higher than the rate observed in individuals with clinically defined FH. The risk of CAD and AMI was increased to varying degrees in subjects with different FH risk alleles. Close monitoring and risk stratification strategy are essential in high-risk patients with FH risk alleles to facilitate early detection and treatments.

Estimated Yield of Screening for Heterozygous Familial Hypercholesterolemia With and Without Genetic Testing in US Adults

Background Heterozygous familial hypercholesterolemia (FH) is a common genetic disorder causing premature cardiovascular disease. Despite this, there is no national screening program in the United States to identify individuals with FH or likely pathogenic FH genetic variants. Methods and Results The clinical characteristics and FH variant status of 49 738 UK Biobank participants were used to develop a regression model to predict the probability of having any FH variants. The regression model and modified Dutch Lipid Clinic Network criteria were applied to 39 790 adult participants (aged ≥20 years) in the National Health and Nutrition Examination Survey to estimate the yield of FH screening programs using Dutch Lipid Clinic Network clinical criteria alone (excluding genetic variant status), genetic testing alone, or combining clinical criteria with genetic testing. The regression model accurately predicted FH variant status in UK Biobank participants (observed prevalence, 0.27%; predicted, 0.26%; area under the receiver-operator characteristic curve, 0.88). In the National Health and Nutrition Examination Survey, the estimated yield per 1000 individuals screened (95% CI) was 3.7 (3.0-4.6) FH cases with the Dutch Lipid Clinic Network clinical criteria alone, 3.8 (2.7-5.1) cases with genetic testing alone, and 6.6 (5.3-8.0) cases by combining clinical criteria with genetic testing. In young adults aged 20 to 39 years, using clinical criteria alone was estimated to yield 1.3 (95% CI, 0.6-2.5) FH cases per 1000 individuals screened, which was estimated to increase to 4.2 (95% CI, 2.6-6.4) FH cases when combining clinical criteria with genetic testing. Conclusions Screening for FH using a combination of clinical criteria with genetic testing may increase identification and the opportunity for early treatment of individuals with FH.

Cascade Screening for Familial Hypercholesterolemia in South Africa: The Wits FIND-FH Program

OBJECTIVE

Due to gene founder effects, familial hypercholesterolemia (FH) has a prevalence of ≈1:80 in populations of Afrikaner ancestry and is a major contributor to premature atherosclerotic cardiovascular disease in South Africans of Jewish and Indian descent. No systematic program exists to identify these families. Furthermore, information regarding FH prevalence in Black Africans is sparse. The Wits FIND-FH program was initiated in late 2016 to address these issues. Approach and Results: Based on index subjects with definite or probable FH, first-degree relatives were contacted, informed consent obtained, and targeted medical history, physical examination, and blood samples collected. In patients with likely FH using the Simon Broome criteria, DNA analysis for LDLR (low-density lipoprotein receptor), APOB (apolipoprotein B), PCSK9 (proprotein convertase subtilisin/kexin type 9), and LDLRAP1 (LDLR adaptor protein 1) variants was analyzed by next-generation sequencing. Of the initial 700 subjects screened of whom 295 (42%) were index cases, 479 (68.4%) were clinically diagnosed with probable or definite FH. Genetic analysis confirmed 285 of 479 (59.5%) as having variants consistent with FH. Three subjects met the clinical diagnosis for homozygous FH, but DNA analysis revealed a further 34 patients, including 4 Black African subjects, with ≥2 FH-causing variants.

CONCLUSIONS

Using phenotype cascade screening, the Wits FIND-FH program has screened an average of 30 subjects monthly of whom 68% had a clinical diagnosis of FH with ≈60% genetically confirmed. The program is identifying a small but growing number of Black South Africans with FH. Interestingly, 37 subjects (7.7%) who underwent DNA testing were found to have ≥2 FH-causing variants.