Case Report: Next Generation Sequencing in Clinical Practice–A Real Tool for Ending the Protracted Diagnostic Odyssey

We reported a case of sitosterolemia, which is a rare genetic disease, characterized by increased plant sterol absorption and great heterogeneity of clinical manifestations. Our patient was initially referred to the lipid clinic due to high cholesterol levels and premature cardiovascular disease. Diagnosis of familial hypercholesterolemia was established in accordance with the Dutch Lipid Clinic Network criteria. Next-generation sequencing was later performed, which revealed a nonsense mutation in the ABCG8 gene, which led to the diagnosis of sitosterolemia. The aim of our report is to demonstrate, how genetic testing helped to make the correct diagnosis and to explain many of the patient's health problems, which etiology remained unclear for many years.

PCSK9 Inhibitors in Clinical Practice: Experience of a Specialized Lipid Center

Aim. To characterize patients receiving PCSK9 inhibitors, and assess the efficiency of their treatment in a specialized lipid center.Material and methods. A retrospective analysis of the medical records of patients who visited the Lipid clinic of the National Medical Research Center for Therapy and Preventive Medicine (Moscow, Russia), receiving PCSK9 inhibitor and having lipid profile in dynamics, was carried out (n=77). Cardiovascular risk (CVR) and low-density lipoprotein cholesterol (LDL-C) target levels were evaluated in accordance with the Russian guidelines for the diagnostics and correction of dyslipidemias 2020.Results. Of 77 patients taking PCSK9 inhibitors (44.2% males, the median of age 56 [47; 66] years), the majority (64.0%) had a probable or definite familial hypercholesterolemia (FH). The proportion of other lipid metabolism disorders, pure hypercholesterolemia and combined hyperlipidemia was 21% and 15%. More than half of the patients (68.8%) had a very high CVR, mainly due to the presence of coronary heart disease (84.9%). The proportion of patients receiving PCSK9 inhibitors as monotherapy was 7.8%, in combination with high-intensity statin therapy – 33.8%, as part of triple lipid-lowering therapy (high-intensity statin, ezetimibe, PCSK9 inhibitors) – 50.6%. Addition of PCSK9 inhibitors to combined lipid-lowering therapy enabled to reduce the LDL-C level to 1.02 [0.62; 1.39] mmol/l with its total decrease from the baseline by 87.3%. While taking PCSK9 inhibitors, LDL-C <1.8 mmol/l and <1.4 mmol/l achieved at 78.3% and 57.7% FH patients with high and very high CVR, respectively. Among patients with other hyperlipidemias, 74.1% of patients with very high CVR was achieved the target LDL-C level <1.4 mmol/l.Conclusion: In a specialized lipid center, PCSK9 inhibitors are prescribed to patients with high or very high CVR, most of whom are FH patients. The effectiveness of the use of PCSK9 inhibitors in real-world practice is comparable to the results of clinical trials.

The Role of Cumulative LDL Cholesterol in Cardiovascular Disease Development in Patients with Familial Hypercholesterolemia

In patients with familial hypercholesterolemia (FH) the exposure of very high LDL-C concentration and cumulative LDL-C level (cum LDL-C) can play a significant role in the prognosis. Objective: to analyze the contribution of “cum LDL-C for all life” and the index “cum LDL-C/age” to the development of coronary heart disease (CHD), myocardial infarction (MI), and a combined end point: MI, stroke, unstable angina in FH patients. Methods: 188 patients (mean age 49.2 years, males 45.7%) with FH were examined (Dutch Lipid Clinic Criteria). We had evaluated cumulative LDL-C and index “cum DL-C/age” along with other classical risk factors. Cum LDL-C was calculated as LDL-Cmax × (age at initiating of hypolipidemic therapy) + LDL-C at inclusion age at initiation/correction therapy). Cumulative LDL-C and “cum LDL-C/age” were calculated as the ratio cum LDL-C to age. The follow-up period was 5.4 (from 3 to 10) years. Results: The index “cum LDL-C/age” was higher in patients with CHD 58.7 ± 10.4 mmol/L/years vs. 40.1 ± 11.7 mmol/L/years in patients without CHD (p < 0.001). According to our data based on the results of the logistic regression analysis in patients with FH, cumulative LDL-C and the cumulative index “cum LDL–C/age” played a strong predictive role in the development of CHD in FH patients; it was greater than the role of TC and LDL-C concentrations. We present ROC curves for CHD, MI and combined end point in FH patients, and a prognostic scale for CHD development, which is based on classical cardiovascular risk factors. Conclusion: cumulative LDL-C level plays an important role in the development of CHD in FH patients.

Two Novel Disease-Causing Mutations in the LDLR of Familial Hypercholesterolemia

As an autosomal dominant disorder, familial hypercholesterolemia (FH) is mainly caused by pathogenic mutations in lipid metabolism-related genes. The aim of this study is to investigate the genetic mutations in FH patients and verify their pathogenicity. First of all, a pedigree investigation was conducted in one family diagnosed with FH using the Dutch Lipid Clinic Network criteria. The high-throughput sequencing was performed on three family members to explore genetic mutations. The effects of low-density lipoprotein receptor (LDLR) variants on their expression levels and activity were further validated by silico analysis and functional studies. The results revealed that LDLC levels of the proband and his daughter were abnormally elevated. The whole-exome sequencing and Sanger sequencing were used to confirm that there were two LDLR missense mutations (LDLR c.226 G &gt; C, c.1003 G &gt; T) in this family. Bioinformatic analysis (Mutationtaster) indicated that these two mutations might be disease-causing variants. In vitro experiments suggested that LDLR c.226 G &gt; C and c.1003 G &gt; T could attenuate the uptake of Dil-LDL by LDLR. In conclusion, the LDLR c.226 G &gt; C and c.1003 G &gt; T variants might be pathogenic for FH by causing uptake dysfunction of the LDLR.

Estimated Prevalence of Familial Hypercholesterolemia Among Egyptian Patients with Acute Coronary Syndromes; Analysis from The Cardiorisk Project

Aims The prevalence of familial hypercholesterolemia (FH) in Egypt is largely un- known. We aimed to estimate the prevalence of FH among 3224 Egyptian patients with acute coronary syndromes enrolled from 2015 to 2018 in the nationwide cross- sectional cardioRisk project. Methods and Results We applied the Dutch Lipid Clinic criteria for the diagnosis of FH on the available data recorded for the patients enrolled in the CardioRisk project. Two main criteria were applied: the presence of premature CAD (given 2 points in the Dutch criteria), and the categorized low density lipoprotein cholesterol (LDL-C) lev- els (given 1, 3, 5, or 8 points in the Dutch criteria according to the level). From a total of 3224 patients, 2743 patients had available LDL-C levels. Among those patients, when applying the abovementioned 2 criteria, we estimated that 472 patients had at least ‘possible’ FH (17.2% of the total population). Specifically, 4 patients had ‘defi- nite’ FH (0.1%), 7 patients had ‘probable’ FH (0.25%), and 461 patients had ‘possi- ble’ FH (16.8%). Conclusion The estimated prevalence of at least ‘possible’ FH among Egyptian patients with ACS is 17%.

Impact of diabetes on coronary severity and cardiovascular outcomes in patients with heterozygous familial hypercholesterolemia: an analysis of genotype and phenotype

Aims Type 2 diabetes mellitus (T2DM) is an independent risk factor for cardiovascular disease. However, the association between T2DM and coronary artery disease (CAD) in patients with heterozygous familial hypercholesterolemia (HeFH) has not been thoroughly evaluated. Our study aimed to assess the effect of T2DM on CAD severity and hard cardiovascular endpoints in a HeFH cohort. Methods A total of 432 patients with HeFH with a molecular and/or clinical Dutch Lipid Clinic Network score ≥6 (definite and probable) were enrolled. Patients were divided into a T2DM group (n=99) and a non-T2DM group (n=333). Hard endpoints included a composite of non-fatal myocardial infarction, stroke, and cardiac death. Results No differences were observed regarding genetic mutations in patients with and without T2DM. Patients with T2DM demonstrated a greater number of diseased vessels (p=0.029) and more severe coronary lesions with high Gensini, SYNTAX, and Jeopardy score tertiles. Compared with patients without T2DM, patients with T2DM were at a significantly greater risk of hard endpoints (multivariate adjusted hazard ratio [HR] 2.32, 95% confidence interval [CI] 1.02–4.84, p=0.025). Additionally, patients with T2DM and good glucose control (HbA1c &lt;7.0%) were at a lower risk of hard endpoints compared with those with poor glucose control (HbA1c ≥7.0%, HR 0.08, 95% CI 0.01–0.56, p=0.011). Conclusions We conclude that T2DM is an independent predictor of CAD severity when assessed by four different tests and worse cardiovascular outcomes, suggesting that T2DM could be further used for risk stratification of patients with HeFH. FUNDunding Acknowledgement Type of funding sources: None. Graphical abstract

Large-Scale Screening for Monogenic and Clinically Defined Familial Hypercholesterolemia in Iceland

Objective: Familial hypercholesterolemia (FH) is traditionally defined as a monogenic disease characterized by severely elevated LDL-C (low-density lipoprotein cholesterol) levels. In practice, FH is commonly a clinical diagnosis without confirmation of a causative mutation. In this study, we sought to characterize and compare monogenic and clinically defined FH in a large sample of Icelanders. Approach and Results: We whole-genome sequenced 49 962 Icelanders and imputed the identified variants into an overall sample of 166 281 chip-genotyped Icelanders. We identified 20 FH mutations in LDLR , APOB , and PCSK9 with combined prevalence of 1 in 836. Monogenic FH was associated with severely elevated LDL-C levels and increased risk of premature coronary disease, aortic valve stenosis, and high burden of coronary atherosclerosis. We used a modified version of the Dutch Lipid Clinic Network criteria to screen for the clinical FH phenotype among living adult participants (N=79 058). Clinical FH was found in 2.2% of participants, of whom only 5.2% had monogenic FH. Mutation-negative clinical FH has a strong polygenic basis. Both individuals with monogenic FH and individuals with mutation-negative clinical FH were markedly undertreated with cholesterol-lowering medications and only a minority attained an LDL-C target of <2.6 mmol/L (<100 mg/dL; 11.0% and 24.9%, respectively) or <1.8 mmol/L (<70 mg/dL; 0.0% and 5.2%, respectively), as recommended for primary prevention by European Society of Cardiology/European Atherosclerosis Society cholesterol guidelines. Conclusions: Clinically defined FH is a relatively common phenotype that is explained by monogenic FH in only a minority of cases. Both monogenic and clinical FH confer high cardiovascular risk but are markedly undertreated.

Comparing the performance of the novel FAMCAT algorithms and established case-finding criteria for familial hypercholesterolaemia in primary care

ObjectiveFamilial hypercholesterolaemia (FH) is a common inherited disorder causing premature coronary heart disease (CHD) and death. We have developed the novel Familial Hypercholesterolaemia Case Ascertainment Tool (FAMCAT 1) case-finding algorithm for application in primary care, to improve detection of FH. The performance of this algorithm was further improved by including personal history of premature CHD (FAMCAT 2 algorithm). This study has evaluated their performance, at 95% specificity, to detect genetically confirmed FH in the general population. We also compared these algorithms to established clinical case-finding criteria.MethodsProspective validation study, in 14 general practices, recruiting participants from the general adult population with cholesterol documented. For 260 participants with available health records, we determined possible FH cases based on FAMCAT thresholds, Dutch Lipid Clinic Network (DLCN) score, Simon-Broome criteria and recommended cholesterol thresholds (total cholesterol >9.0 mmol/L if ≥30 years or >7.5 mmol/L if <30 years), using clinical data from electronic and manual extraction of patient records and family history questionnaires. The reference standard was genetic testing. We examined detection rate (DR), sensitivity and specificity for each case-finding criteria.ResultsAt 95% specificity, FAMCAT 1 had a DR of 27.8% (95% CI 12.5% to 50.9%) with sensitivity of 31.2% (95% CI 11.0% to 58.7%); while FAMCAT 2 had a DR of 45.8% (95% CI 27.9% to 64.9%) with sensitivity of 68.8% (95% CI 41.3% to 89.0%). DLCN score ≥6 points yielded a DR of 35.3% (95% CI 17.3% to 58.7%) and sensitivity of 37.5% (95% CI 15.2% to 64.6%). Using recommended cholesterol thresholds resulted in DR of 28.0% (95% CI 14.3% to 47.6%) with sensitivity of 43.8% (95% CI 19.8% to 70.1%). Simon-Broome criteria had lower DR 11.3% (95% CI 6.0% to 20.0%) and specificity 70.9% (95% CI 64.8% to 76.5%) but higher sensitivity of 56.3% (95% CI 29.9% to 80.2%).ConclusionsIn primary care, in patients with cholesterol documented, FAMCAT 2 performs better than other case-finding criteria for detecting genetically confirmed FH, with no prior clinical review required for case finding.Trial registration numberNCT03934320.