Genetic Diagnosis Of Familial Hypercholesterolemia Research Articles

APOE and familial hypercholesterolemia.

Autosomal dominant hypercholesterolemia is a common cause of cardiovascular disease. In addition to the classic genes that cause hypercholesterolemia, LDLR, APOB and PCSK9, a new locus has emerged as a candidate to be the cause of this hyperlipidemia, the p.(Leu167del) mutation in the APOE gene. Various studies have demonstrated the involvement of the p.(Leu167del) mutation in the APOE gene in hypercholesterolemia: Studies of family segregation, lipoprotein composition by ultracentrifugation and proteomic techniques, and functional studies of VLDL-carrying p.(Leu167del) internalization with cell cultures have demonstrated the role of this mutation in the cause of hypercholesterolemia. The phenotype of individuals carrying the p.(Leu167del) in APOE is indistinguishable from familial hypercholesterolemia individuals with mutations in the classic genes. However, a better response to lipid-lowering treatment has been demonstrated in these APOE mutation carrier individuals. Therefore, APOE gene should be considered a candidate locus along with LDLR, APOB, and PCSK9 to be investigated in the genetic diagnosis of familial hypercholesterolemia.

Circulating miR-6821-5p levels and coronary calcification in asymptomatic familial hypercholesterolemia patients

Background and aimsPremature atherosclerotic cardiovascular disease (CVD) is a clinic characteristic of familial hypercholesterolemia (FH). Coronary calcium score (CCS) is a highly used imaging modality to evidence atherosclerotic plaque burden. microRNAs (miRNAs) are non-coding RNAs that epigenetically regulate gene expression. Here, we investigated whether CCS associates with a specific miRNA-signature in FH-patients. MethodsPatients with genetic diagnosis of FH (N = 86) from the nationwide SAFEHEART-cohort were investigated by computed tomography angiography imaging and classified depending on the presence of coronary calcification in FH-CCS (+) and FH-CCS (−) groups by the Agatston score. Differential miRNA profiling was performed in two stages: first by Affymetrix microarray technology (high-throughput differential profiling-studies) and second by RT-PCR using TaqMan-technology (analytical RT-qPCR study) in plasma of the two patient groups. ResultsmiR-193a-5p, miR-30e-5p and miR-6821-5p levels were significantly higher in FH-CCS (+) compared to FH-CCS (−). miR-6821-5p was the best miRNA to discriminate FH-patients CCS(+), according to receiver operating characteristic (ROC) analysis (AUC: 0.70 ± 0.06, p = 0.006). High miR-6821-5p levels were associated with older age (p = 0.03) and high LDL-burden (p = 0.014) using a ROC-derived cut-off value. However, miR-6821-5p did not correlate with age in either the CCS- or CCS + group. Genes involved in calcification processes were identified by in silico analysis. The relation of cell-calcification and expression levels of miR-6821-5p, BMP2 and SPP1 was validated experimentally in human vascular smooth muscle cell cultures. ConclusionsUp-regulated levels of miR-6821-5p are found in the plasma of asymptomatic FH-patients with coronary calcified atherosclerotic plaques, as well as in isolated human vascular smooth muscle cells expressing the pro-calcification genes BMP2 and SPP1. These findings highlight the impact of epigenetic regulation on the development of subclinical atherosclerosis.

Clinical and genetic diagnosis of familial hypercholesterolaemia in patients undergoing coronary angiography: the Ludwigshafen Risk and Cardiovascular Health Study.

To investigate the prevalence of familial hypercholesterolaemia (FH) and compare the performance of clinical criteria and genetic testing in patients undergoing coronary angiography. The prevalence of FH was determined with the Dutch Lipid Clinical Network (DLCN), US-MEDPED, Simon Broome (SB) criteria, the 'Familial Hypercholesterolaemia Case Ascertainment Tool' (FAMCAT), and a clinical algorithm. Genetic screening was conducted with a custom array from Affymetrix (CARRENAL array) harboring 944 FH mutations. The study cohort consisted of 3267 patients (78.6% with coronary artery disease [CAD]). FH was diagnosed in 2.8%, 2.2%, 3.9%, and 7.9% using the DLCN, US-MEDPED, SB criteria, and the FAMCAT. The clinical algorithm identified the same patients as the SB criteria. Pathogenic FH mutations were found in 1.2% (1.2% in patients with CAD, 1.0% in patients without CAD). FH was more frequently diagnosed in younger patients. With genetic testing as reference, the clinical criteria achieved areas under the ROC curve (AUCs) in the range of 0.56-0.68. Using only LDL-C corrected for statin intake, an AUC of 0.68 was achieved. FH is up to fourfold more prevalent in patients undergoing coronary angiography than in contemporary cohorts representing the general population. Different clinical criteria yield substantially different diagnosis rates, overestimating the prevalence of FH compared to genetic testing. LDL-C testing alone may be sufficient to raise the suspicion of FH, which then needs to be corroborated by genetic testing.

A new 165-SNP low-density lipoprotein cholesterol polygenic risk score based on next generation sequencing outperforms previously published scores in routine diagnostics of familial hypercholesterolemia

Genetic diagnosis of familial hypercholesterolemia (FH) remains unexplained in 30 to 70% of patients after exclusion of monogenic disease. There is now a growing evidence that a polygenic burden significantly modulates LDL-cholesterol (LDL-c) concentrations. Several LDL-c polygenic risk scores (PRS) have been set up. However, the balance between their diagnosis performance and their practical use in routine practice is not clearly established. Consequently, we set up new PRS based on our routine panel for sequencing and compared their diagnostic performance with previously-published PRS. After a meta-analysis, four new PRS including 165 to 1633 SNP were setup using different softwares. They were established using two French control cohorts (MONA LISA n=1082 and FranceGenRef n=856). Then the explained LDL-c variance and the ability of each PRS to discriminate monogenic negative FH patients (M-) versus healthy controls were compared with 4 previously-described PRS in 785 unrelated FH patients. Between all PRS, the 165-SNP PRS developed with PLINK showed the best LDL-c explained variance (adjusted R²=0.19) and the best diagnosis abilities (AUROC=0.77, 95%CI=0.74-0.79): it significantly outperformed all the previously-published PRS (p<1 × 10−4). By using a cut-off at the 75th percentile, 61% of M- patients exhibited a polygenic hypercholesterolemia with the 165-SNP PRS versus 48% with the previously published 12-SNP PRS (p =3.3 × 10−6). These results were replicated using the UK biobank. This new 165-SNP PRS, usable in routine diagnosis, exhibits better diagnosis abilities for a polygenic hypercholesterolemia diagnosis. It would be a valuable tool to optimize referral for whole genome sequencing.

Implementation of a biochemical, clinical, and genetic screening programme for familial hypercholesterolemia in 26 centres in Spain: The ARIAN study.

Background: Familial hypercholesterolemia (FH) is clearly underdiagnosed and undertreated. The aim of this present study is to assess the benefits of FH screening through a joint national program implemented between clinical laboratories and lipid units. Methods: All clinical laboratory tests from 1 January 2017 to 31 December 2018 were reviewed, and those with LDL cholesterol (LDL-C) levels >250 mg/dl were identified in subjects >18 years of age of both sexes. Once secondary causes had been ruled out, the treating physician was contacted and advised to refer the patient to an LU to perform the Dutch Lipid Clinic Network score and to request genetic testing if the score was ≥6 points. Next Generation Sequencing was used to analyse the promoter and coding DNA sequences of four genes associated with FH (LDLR, APOB, PCSK9, APOE) and two genes that have a clinical overlap with FH characteristics (LDLRAP1 and LIPA). A polygenic risk score based on 12 variants was also obtained. Results: Of the 3,827,513 patients analyzed in 26 centers, 6,765 had LDL-C levels >250 mg/dl. Having ruled out secondary causes and known cases of FH, 3,015 subjects were included, although only 1,205 treating physicians could be contacted. 635 patients were referred to an LU and genetic testing was requested for 153 of them. This resulted in a finding of sixty-seven pathogenic variants for FH, 66 in the LDLR gene and one in APOB. The polygenic risk score was found higher in those who had no pathogenic variant compared to those with a pathogenic variant. Conclusion: Despite its limitations, systematic collaboration between clinical laboratories and lipid units allows for the identification of large numbers of patients with a phenotypic or genetic diagnosis of FH, which will reduce their vascular risk. This activity should be part of the clinical routine.

Fast and Easy Nanopore Sequencing Workflow for Rapid Genetic Testing of Familial Hypercholesterolemia.

Familial hypercholesterolemia (FH) is an autosomal dominant lipid metabolism disorder characterized by severely elevated plasma low-density lipoprotein cholesterol levels. The disease is caused by mutations in 3 genes (LDLR, APOB and PCSK9) while over 90% of the mutations are located within the LDLR gene. Thus, genetic analysis of the LDLR gene is the first step in the genetic diagnosis of FH. However, conventional methods like Sanger and NextGen sequencing are still costly and time-consuming. In contrast, Oxford Nanopore technology sequencing is an emerging third-generation sequencing technology featured by easy operability, low cost, small size and the capability of parallel sample sequencing. Here, we present an easy Nanopore-sequencing-based workflow for the rapid genetic testing of FH taking only 3 days and costing less than $50 per sample without the requirement for deep bioinformatic knowledge. Using our workflow, we were able to identify the underlying pathogenic variants of 10 FH patients including one novel, not yet recorded pathogenic variants. Our workflow allows the rapid evaluation of the pathogenic variants by utilizing detailed variant information from Ensembl. Additionally, our workflow is not restricted to sequencing the LDLR gene alone but can be easily adapted to the other FH-causing genes and more importantly, to any desired gene contributing to any hereditary disease. Therefore, our workflow is an attractive opportunity for every diagnostic laboratory to offer fast and easy in-house genetic diagnostics.

Polygenic contribution for familial hypercholesterolemia (FH).

The present review summarizes different polygenic risk scores associated with hypercholesterolemia applied to cohorts with a genetic diagnosis of familial hypercholesterolemia (FH). Several single-nucleotide polymorphisms associated with increased levels of LDL-C or Lp(a) have been genotyped in population cohorts with FH phenotype, to identify the cause of hypercholesterolemia in mutation negative individuals. In different studies, a large proportion of individuals without a monogenic causative variant (in low density lipoprotein receptor gene (LDLR), apolipoprotein B gene (APOB) or proprotein convertase subtilisin/kexin type 9 gene (PCSK9 genes) was considered to have a hypercholesterolemia with a polygenic basis. The heterogeneity in the phenotype of monogenic FH may also be explained by polygenic contributions to LDL-C. The elevated LDL-C genetic risk score (GRS) has been associated with increased risk of atherosclerotic cardiovascular disease in individuals with monogenic FH. Moreover, a poorer response to lipid lowering therapy has been associated with monogenic FH when compared to a polygenic basis. The reason why Lp(a) concentrations are raised in individuals with clinical FH is unclear, but it could be caused by a genetic variation in Lipoprotein(A) gene as a polygenic contribution. Polygenic risk scores have revealed to be important tools to define the cause of hypercholesterolemia in FH mutation-negative individuals and should be included in FH diagnosis strategies, although there is still space for more specific LDL-C GRS to be developed. The use of GRS may be used to refine cardiovascular risk prediction in FH patients and could lead to a personalized approach to therapy. The identification of the genetic status of an individual with FH phenotype (monogenic or polygenic) may have implications on their risk stratification, cascade screening of relatives, disease management and therapeutic measures.

Abstract 13685: Combined Genetic Defects of Sitosterolemia and Familial Hypercholesterolemia

Background: Familial hypercholesterolemia (FH) is an inherited disorder caused by mutations in the genes in the LDL receptor pathway, including LDLR , PCSK9 , APOB, and ARH . Defective uptake of LDL by the liver increases plasma LDL-cholesterol (LDL-C) levels, leading to an increased risk of coronary heart disease. The differential diagnosis of FH includes sitosterolemia which is a rare autosomal recessive disorder caused by mutations in ABCG5 or ABCG8 . Case presentation: Here we present a rare case of sitosterolemia with a genetic diagnosis of FH. A 64-years-old woman, clinically diagnosed as FH with Achilles tendon thickness (&gt;18 mm on X-ray imaging), had been taking statins only intermittently due to muscle pains. The combinatorial therapy with ezetimibe decreased her plasma LDL-C levels to around 90-250 mg/dL with variable adherence to statins and dietary management. Further addition of a PCSK9 inhibitor (evolocumab) was largely ineffective with plasma LDL-C levels of 90-190 mg/dL. A systemic medical evaluation revealed persistent joint pains of unknown etiology and slightly decreased platelet count. These clinical features led us to suspect sitosterolemia. Biochemical and genetic analyses: Plasma concentration of sitosterol was elevated (16.8 mg/dL). Genetic testing was performed after obtaining informed consent. All procedures were subjected to approval by the human genome, gene analysis research ethics committee of the University of Tokyo. In addition to a heterozygous missense mutation in LDLR (p.Arg115His), a homozygous nonsense mutation in ABCG5 (p.Tyr188Ter) was identified. No rare variants were found in PCSK9 nor ABCG8 . Conclusions: To our knowledge, this is the first case of a combined genetic defect of sitosterolemia and FH. Atypical clinical manifestations such as large fluctuations of LDL-C levels, unresponsiveness to a PCSK9 inhibitor, arthralgia, and a reduced platelet count led to the genetic diagnosis. Our case is informative in the perspective of precision medicine, highlighting the importance of systemic medical evaluation to select patients who will be benefited more from genetic testing as well as the necessity of future drug development for this rare and intractable disease.

Lipoprotein (a) in patients with a genetic diagnosis of familial hypercholesterolaemia in Southern Bulgaria

Background and Aims: Lipoprotein (a) (Lp (a) is one of the main reasons for the large residual risk in patients with Familial hypercholesterolemia (FH). The goal of the study was to analyse the Lp (a) levels in 300 patients with a genetically proven hetero-FH.

Improving the identification of patients with a genetic diagnosis of familial hypercholesterolaemia in primary care: A strategy to achieve the NHS long term plan

Background and aimsWe aimed to validate a nurse-led process using electronic health records to identify those at risk of familial hypercholesterolaemia (FH) for genetic diagnosis in primary care. MethodsThose at risk of FH were identified using searches developed and refined locally and implemented in primary care by a trained nurse; they were invited for further assessment and genetic testing if indicated. Family members at risk of FH were identified and invited for cascade testing. ResultsIn total 94,444 patient records were screened (expected prevalence of FH (1 in 250); 377). Of 176 records which already had a diagnostic for FH, 15 had been genetically confirmed and one was undergoing DNA testing. A further 572 (0.61%) were identified as high risk of FH. After desktop screening, 113 (15%) were invited for further assessment. Of these, 73 individuals attended the primary care clinic (64%) of whom 61 (54%) underwent proband genetic testing. Pathogenic variants were detected in 22 cases (36%) and variants of unknown significance in a further 4 cases; a total of 26 probands (43%) were therefore referred for family cascade testing. ConclusionsAn optimised FH identification pathway, based on the NICE CG71 recommendations for systematic searching of primary care electronic health records, can be deployed successfully in primary care settings.

Familial Hypercholesterolemia: A Narrative Review on Diagnosis and Management Strategies for Children and Adolescents.

Familial hypercholesterolemia (FH) is a relatively common inherited disorder caused by deleterious mutation(s) in the low-density lipoprotein (LDL) receptor or its associated genes. Given its nature as a heritable disease, any useful screening scheme, including universal, and cascade screening, allows for the early identification of patients with FH. Another important aspect to note is that early diagnosis associated with appropriate treatment can promote better prognosis. However, most clinical diagnostic criteria for adults have adopted clinical elements, such as physical xanthomas and family history, both of which are usually obscure and/or difficult to obtain in children and adolescents. Moreover, LDL cholesterol levels fluctuating considerably during adolescence, hindering the timely diagnosis of FH. In addition, recent advancements in human genetics have revealed several types of FH, including conventional monogenic FH, polygenic FH caused by common single nucleotide variations (SNV) accumulation associated with elevated LDL cholesterol, and oligogenic FH with multiple deleterious genetic variations leading to substantially elevated LDL cholesterol. The aforementioned findings collectively suggest the need for amassing information related to genetics and imaging, in addition to classical clinical elements, for the accurate diagnosis of FH in this era of personalized medicine. The current narrative review summarizes the current status of the clinical and genetic diagnosis of FH in children and adolescents, as well as provide useful management strategies for FH in children and adolescents based on currently available clinical evidence.

Correlation between different LDL-R mutations and response to AB-PCSK9 therapy in a group of patient with genetic diagnosis of familial hypercholesterolemia

Correlation between different LDL-R mutations and response to AB-PCSK9 therapy in a group of patient with genetic diagnosis of familial hypercholesterolemia

Cascade screening and genetic diagnosis of familial hypercholesterolemia in clusters of the Southeastern region from Brazil.

Familial hypercholesterolemia (FH) is an autosomal dominant genetic disease characterized by high levels of low-density lipoprotein-cholesterol (LDLc), associated to premature cardiovascular disease. The detection of the variants related to FH is important to improve the early diagnosis in probands / index-cases (ICs) and their relatives. We included ICs with FH and their relatives, living in a small region of Minas Gerais state-Brazil, which were classified according to Dutch Lipid Clinic Network Criteria (DLCNC) and submitted to sequencing of genes related to FH (LDLR, APOB, PCSK9, LDLRAP1, LIPA, STAP1, APOE, ABCG5 e ABCG8). In a total of 143 subjects (32 ICs and 111 relatives), eight variants were identified in 91 individuals. From these variants, five were in LDLR [p.(Asp224Asn), p.(Ser854Gly), p.(Cys34Arg), p.(Asp601His), deletion of exon15 in LDLR)], one in APOB [p.(Met499Val)], one in PCSK9 [p.(Arg237Trp)] and one in APOE [p.(Pro28Leu)] genes. The variants were detected in 100% of those subjects classified as definitive, 87% as probable and 69% as possible FH cases based on DLCNC. The LDLc level was higher in individuals with corneal arch and xanthomas or xanthelasmas, as well as in pathogenic or probably pathogenic variants carriers. This study showed higher frequency of LDLR gene variants compared to other genes related to LDL metabolism in individuals with FH in Minas Gerais - Brazil and the presence of FH in relatives without previous diagnosis. Our data reinforce the importance of molecular and clinical evaluation of FH relatives in order to early diagnosis the FH, as well as cardiovascular diseases prevention.

Abstract 15576: Cardiovascular Disease in Elderly Familial Hypercholesterolemia Individuals Attending a Cascade Screening Program

Introduction: Familial hypercholesterolemia (FH) is associated with early onset of cardiovascular disease (CVD) and mortality. Lipid lowering treatment (LLT) may change the natural history of FH, however there is scant information about elderly individuals (older than 60 years) with FH. This study describes characteristics of elderly FH individuals presenting or not CVD. Hypothesis: Monogenic defects are important markers of CVD risk and initiation and long-term use of lipid lowering therapy (LLT) is relevant to minimize this risk. Methods: Cross-sectional analysis of clinical and laboratory of molecularly proven elderly FH (FH+) and non-affected (FH-) individuals attending a cascade screening program. FH+ were divided in those presenting or not CVD (defined as previous myocardial infarction or ischemic stroke, carotid or coronary revascularization and angina with stenosis ≥50% on angiography). Results: From 4,111 genotyped individuals, 462 (11.2%) elders were included (198 FH+ and 264 FH-). There was predominance of females in either groups, however with more men in FH+ 37.4% vs. 24.2%, p=0.002. No differences were seen between FH+ and FH- regarding age, [median (%25;75%)] 66 (62;71) and 66 (63;71) years, p=0.68; use of LLT 88.5% vs. 91.5%, p=0.29 and high intensity LLT 61.7 % vs. 55.8%, p=0.20, respectively. Despite longer LLT duration in FH+ 11(7;20) vs. 7 (3;13) years, p&lt;0.001, in either groups LLT was started late, at 54 (47;61) and 59 (52;64) years, p &lt;0.001, respectively in FH+ and FH-. FH+ had higher LDL-C at diagnosis, 243 (179;302) vs. 228 (209;251) mg/dL, p=0.013, as well as greater frequencies of previous CVD 40.9% vs. 27.3%, p=0.002, and early CVD 22.2% vs. 9.0%, p&lt;0.001. In FH+, male sex [OR (95%CI)] 5.29 (2.25-12.45), p&lt;0.001, and use of high intensity LLT 2.51 (1.08-5.87), p=0.03, were independently associated with CVD. Conclusions: The genetic diagnosis of FH was associated with higher rates of CVD and early CVD vs. FH- hypercholesterolemics. Elders with FH+ who survived despite late LLT initiation have a worse CVD history than FH- elders, emphasizing the relevance of a monogenic defect as cause of long-lasting hypercholesterolemia and CVD risk, particularly in men.

Correlation between different LDL-R mutations and response to ab-PCSK9 therapy in a group of patient with genetic diagnosis of Familial Hypercholesterolemia. Preliminary report

Abstract Introduction Familial hypercholesterolemia (FH) is an autosomal dominant disease that leads to premature cardiovascular disease (CAD). The availability of ab-PCSK9 has changed the approach to therapy. Purpose To evaluate the relationship between different types of mutations in LDLR gene and response to ab-PCSK9. Methods 73 FH patients, 33 women and 40 men (53.9±13. yrs), in primary prevention (N=46) and secondary prevention (N=27), were recruited. This sample included patients with mutations in LDLR gene: heterozygotes for missense mutations (N=31), for null mutations (N=31), compound heterozygotes or homozygotes (N=11). At baseline, the whole sample had a maximally tolerated lipid lowering therapy (MT-LLT) without ab-PCSK9; 16 patients had MT-LLTs intolerance. After 160 days with ab-PCSK9 therapy we evaluated the achievement of a goal (LDL-C&amp;lt;70 mg/dL in primary prevention without Diabetes Mellitus, LDL-C&amp;lt;55 mg/dL). Results After 160 days of therapy with ab-PCSK9 (45 patients on Alirocumab, 28 patients on Evolocumab) and MT-LLT, 29/73 patients (39.7%) of the whole sample achieve the goal of LDL-C. Of them 14/29 (48.2%) were in primary prevention, 15/29 (51.7%) in secondary prevention, no difference in achievement of the goal. We then evaluated the percent of patients achieving the goal of LDL-C: 15/31 (48.3%) patients with missense mutation and 14/31 (45.1%) patients with null mutation, no significant difference among groups; 0/11 compound heterozygotes or homozygotes; 3/16 (18.7%) MT-LLTs intolerance. The other main cardiovascular risk factors did not influence of the achievement the goal of LDL cholesterol. Conclusions Lack of correlation between type of mutation in heterozygous FH patients and ab-PCSK9 therapy response; response was significantly poorest in patients with compound heterozygosis or homozygosis mutation as compared to heterozygotes; the intolerance to MT-LLT was significant in the achievement of the goal of LDL-C. Different between guideline 2016 vs 2019 Funding Acknowledgement Type of funding source: None

High miR-133a levels in the circulation anticipates presentation of clinical events in familial hypercholesterolaemia patients.

Presentation of acute events in patients with atherosclerosis remains unpredictable even after controlling for classical risk factors. MicroRNAs (miRNAs) measured in liquid biopsies could be good candidate biomarkers to improve risk prediction. Here, we hypothesized that miRNAs could predict atherosclerotic plaque progression and clinical event presentation in familial hypercholesterolaemia (FH) patients. Circulating miRNAs (plasma, exosomes, and microvesicles) were investigated by TaqMan Array and RT-qPCR assays. Patients with genetic diagnosis of FH and healthy relatives from the SAFEHEART cohort were included. A differential signature of 10 miRNA was obtained by comparing two extreme phenotypes consisting of FH patients suffering a cardiovascular event (CVE) within a 8-year follow-up period (FH-CVE, N = 42) and non-FH hypercholesterolaemic relatives from the same cohort, matched for age and treatment, without CVE during the same period (nFH-nCVE, N = 30). The validation studies included two independent groups of patients with FH background (discovery group, N = 89, validation group N = 196), developing a future CVE (FH-CVE) or not (FH-nCVE) within the same time period of follow-up. Of the 10 miRNAs initially selected, miR-133a was significantly higher in FH-CVE than in FH-nCVE patients. Receiver operating characteristic analysis confirmed miR-133a as the best microRNA for predicting CVE in FH patients (0.76 ± 0.054; P < 0.001). Furthermore, Kaplan-Meier and COX analysis showed that high plasma miR-133a levels associated to the higher risk of presenting a CVE within the next 8 years (hazard ratio 3.89, 95% confidence interval 1.88-8.07; P < 0.001). In silico analysis of curate biological interactions related miR-133a with target genes involved in regulation of the cell-membrane lipid-receptor LRP6 and inflammatory cytokines (CXCL8, IL6, and TNF). These predictions were experimentally proven in human macrophages and endothelial cells transfected with agomiR-133a. Elevated levels of miR-133a in the circulation anticipate those FH patients that are going to present a clinical CVE within the next 2 years (average). Mechanistically, miR-133a is directly related with lipid- and inflammatory signalling in key cells for atherosclerosis progression.

Widening the spectrum of genetic testing in familial hypercholesterolaemia: Will it translate into better patient and population outcomes?

Familial hypercholesterolaemia (FH) is caused by pathogenic variants in LDLR, APOB or PCSK9. Impaired low-density lipoprotein (LDL) receptor function leads to decreased LDL catabolism and premature atherosclerotic cardiovascular disease (ASCVD). Thousands of LDLR variants are known, but assignation of pathogenicity requires accurate phenotyping, family studies and assessment of LDL receptor function. Precise, genetic diagnosis of FH using targeted next generation sequencing allows for optimal treatment, distinguishing FH from pathogenically distinct disorders requiring different treatment. Polygenic hypercholesterolaemia resulting from an accumulation of LDL cholesterol-raising single nucleotide polymorphisms (SNPs) could also be suspected by this approach. Similarly, ASCVD risk could be estimated by broader sequencing of cholesterol and non-cholesterol-related genes. Both of these areas require further research. The clinical management of FH, focusing on the primary or secondary prevention of ASCVD, has been boosted by PCSK9 inhibitor therapy. The efficacy of PCSK9 inhibitors in homozygous FH may be partly predicted by the LDLR variants. While expanded genetic testing in FH is clinically useful in providing an accurate diagnosis and enabling cost-effective testing of relatives, further research is needed to establish its value in improving clinical outcomes.

Individuals with familial hypercholesterolemia and cardiovascular events have higher circulating Lp(a) levels

Cardiovascular disease (CVD) is a major cause of mortality and morbidity. Increased low-density lipoprotein cholesterol (LDL-C) level is its major risk factor. Familial hypercholesterolemia (FH) is a genetic disorder characterized by elevated LDL-C since birth and subsequent premature CVD. There is a heterogeneity in the CVD onset in patients with FH. This is potentially due to the presence of other independent risk factors. Lipoprotein(a) [Lp(a)] is an LDL-like particle and represents a strong risk factor for CVD. Our objective was to understand the contribution of Lp(a) in the susceptibility to CVD in individuals with genetic diagnosis of FH. We measured Lp(a) levels in 2 independent and well-characterized genetic-FH cohorts: the FH-Gothenburg cohort (n=190) and the FH-CEGP Milan cohort (n=160). The genetic diagnosis was performed by targeted next-generation sequencing (FH-Gothenburg and part of the FH-CEGP Milan cohort), or by Sanger sequencing. We show that among individuals with genetic diagnosis of FH, those with previous CVD had higher Lp(a) levels. In addition, analyzing the response to the lipid-lowering therapies, we have also shown that statins had the same LDL-C-lowering effect irrespective of the type of FH-causative mutation. However, when we examined the lipid-lowering effect of proprotein convertase subtilisin/kexin type 9 inhibition by antibodies, we observed a trend in a better reduction of the LDL-C level in carriers of nonsense mutations. In conclusion, our results suggest that Lp(a) contributes to CVD onset in individuals with genetic diagnosis of FH. Our finding supports the importance to identify an efficacious therapy to lower Lp(a) in patients with FH to prevent CVD onset or recurrence.

The island of Gran Canaria: A genetic isolate for familial hypercholesterolemia

Genetic diagnosis of familial hypercholesterolemia (FH) has not been universally performed in the Canary Islands (Spain). This study aimed to genetically characterize a cohort of patients with FH in the island of Gran Canaria. Study subjects were 70 unrelated index cases attending a tertiary hospital in Gran Canaria, with a clinical diagnosis of FH, according to the criteria of the Dutch Lipid Clinic Network. Given that 7 of the first 10 cases with positive genetic study were carriers of a single mutation in the LDLR gene [p.(Tyr400_Phe402del)], a specific polymerase chain reaction-based assay was developed for the detection of this variant as a first screening step on the remaining subjects. In those without this mutation, molecular diagnosis was completed using a next-generation sequencing panel including LDLR, APOB, PCSK9, LDLRAP1, APOE, STAP1, and LIPA genes and incorporating copy number variation detection in LDLR. On the whole, 44 subjects (62%) had a positive genetic study, of whom 30 (68%) were heterozygous carriers of the p.(Tyr400_Phe402del) variant. Eleven subjects carried other mutations in LDLR, including the novel mutation NM_000527.4: c.877dupG; NP_000518.1: p.(Asp293Glyfs*8). An unclassified PCSK9 gene variant was found in one subject [(NM_174936.3:c.1496G>A; NP_777596.2: p.(Arg499His)]. Other single patients had mutations in APOB (heterozygous) and in LIPA (homozygous). All identified variants co-segregated with the disease phenotype. These findings suggest a founder effect for the p.(Tyr400_Phe402del) LDLR mutation in Gran Canaria. A cost-effective local screening strategy for genetic diagnosis of FH could be implemented in this region.

Molecular diagnosis methods in familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is considered the genetic cause of coronary heart disease and ischemic stroke. FH is mainly an autosomal codominant pattern-based disorder and is primarily determined by point mutations within the low-density lipoprotein receptor, apolipoprotein B, and proprotein convertase subtilisin/kexin type 9 genes, causing increased low-density lipoprotein cholesterol levels in the serum of untreated individuals. The accumulation will eventually lead to atherosclerotic cardiovascular disease. Although clinical criteria comprising several prognosis scores, such as the Simon Broome, Dutch Lipid Clinic Network, Make Early Diagnosis to Prevent Early Death, and the recently proposed Montreal-FH-SCORE, are the conventional basis of diagnosing FH, the genetic diagnosis made by single nucleotide polymorphism genotyping, multiplex ligation-dependent probe amplification analysis, and sequencing (both Sanger and Next-Generation sequencing) offers unequivocal diagnosis. Given the heterogeneity of known mutations, the genetic diagnosis of FH is often difficult to establish, despite the growing evidence of the causative mutations, as well as the polygenic aspect of this pathology and the importance of cascade screening of the FH patient’s healthy family members. This review article details different genetic techniques that can be used in FH identification when there is a clinical FH suspicion based on criteria comprised in prognosis scores, knowing that none of these are exhaustive in the diagnosis, yet they efficaciously overlap and complement each other for confirming the disease at the molecular level.