Clinical Diagnosis Of Familial Hypercholesterolemia Research Articles

Unraveling the genetic background of individuals with a clinical familial hypercholesterolemia phenotype

Familial hypercholesterolemia (FH) is a common genetic disorder of lipid metabolism caused by pathogenic/likely pathogenic variants in LDLR, APOB, and PCSK9 genes. Variants in FH-phenocopy genes (LDLRAP1, APOE, LIPA, ABCG5, and ABCG8), polygenic hypercholesterolemia, and hyperlipoprotein (a) [Lp(a)] can also mimic a clinical FH phenotype. We aim to present a new diagnostic tool to unravel the genetic background of clinical FH phenotype. Biochemical and genetic study was performed in 1,005 individuals with clinical diagnosis of FH, referred to the Portuguese FH Study. A next-generation sequencing panel, covering eight genes and eight SNPs to determine LDL-C polygenic risk score and LPA genetic score, was validated, and used in this study. FH was genetically confirmed in 417 index cases: 408 heterozygotes and 9 homozygotes. Cascade screening increased the identification to 1,000 FH individuals, including 11 homozygotes. FH-negative individuals (phenotype positive and genotype negative) have Lp(a) >50 mg/dl (30%), high polygenic risk score (16%), other monogenic lipid metabolism disorders (1%), and heterozygous pathogenic variants in FH-phenocopy genes (2%). Heterozygous variants of uncertain significance were identified in primary genes (12%) and phenocopy genes (7%). Overall, 42% of our cohort was genetically confirmed with FH. In the remaining individuals, other causes for high LDL-C were identified in 68%. Hyper-Lp(a) or polygenic hypercholesterolemia may be the cause of the clinical FH phenotype in almost half of FH-negative individuals. A small part has pathogenic variants in ABCG5/ABCG8 in heterozygosity that can cause hypercholesterolemia and should be further investigated. This extended next-generation sequencing panel identifies individuals with FH and FH-phenocopies, allowing to personalize each person’s treatment according to the affected pathway.

Abstract 13051: Profiling CD8+ T Cell Activation in Experimental Models With LDL-R Deficiency and in Patients With Familial Hypercholesteroleamia

Introduction and Hypothesis: Familial Hypercholesterolaemia (FH) is a rare genetic disease characterized by elevated plasma cholesterol levels, xanthomas, overt atherosclerosis and premature cardiovascular death. HoFH and severe HeFH present an elevated inflammatory burden and poorly responsive to therapeutics such as anti-PCSK9 monoclonal antibodies. Therefore, innovative approaches to diagnose the severity of the disease and control the over-activation of the immune-inflammatory response in the arterial wall of FH patients should be studied to improve the management of this genetic disease. Here we profiled the activation of CD8+ T lymphocytes from experimental models and with patients with clinical diagnosis of FH. Methods: Immunophenotypic characterization of T cells from WT and LDLR KO mice was performed in vitro and in vivo coupled to proteomics and WB analysis on isolated T cells. CD8 T cell response in FH patients, carrying mutations in the LDLR gene, was profiled. Results: LDLR mRNA expression increased after in vitro activation of CD8, but not CD4 T cells, suggesting a different regulation of cholesterol homeostasis between T cell subsets. LDLR deficiency mainly affected CD8 T cell activation as demonstrated by reduced in vitro and in vivo proliferation and cytokine production after ovalbumin vaccination of LDL-R KO T cells compared to their wild type counterpart. The addition of LDL to serum free media increased CD8 proliferation in WT but not in KO CD8 T cells. Proteomic and WB analysis showed that this phenotype is the consequence of reduced mTORC1 activation and impaired lysosomal organization. The proliferation of CD8 T cells from FH patients was less pronounced compared to sex- and age-matched controls. In addition, CD8 T cells from FH vaccinated for seasonal influenza were tested in vitro with virus-derived peptides, showing a decreased granzyme production compared to CD8 from vaccinated controls. Conclusions: LDLR plays a critical role in regulating the immunometabolic reprogramming of activated CD8 T cells by fuelling the cholesterol-lysosome-mTORC1 axis. Acknowledgments: This study is supported by a Grant from the Italian Ministry of Health: RF-2019-12370896

Searching for new genes associated with the familial hypercholesterolemia phenotype using whole-genome sequencing and machine learning.

One of the most common congenital metabolic disorders is familial hypercholesterolemia. Familial hypercholesterolemia is a condition caused by a type of genetic defect leading to a decreased rate of removal of low-density lipoproteins from the bloodstream and a pronounced increase in the blood level of total cholesterol. This disease leads to the early development of cardiovascular diseases of atherosclerotic etiology. Familial hypercholesterolemia is a monogenic disease that is predominantly autosomal dominant. Rare pathogenic variants in the LDLR gene are present in 75-85 % of cases with an identified molecular genetic cause of the disease, and variants in other genes (APOB, PCSK9, LDLRAP1, ABCG5, ABCG8, and others) occur at a frequency of < 5 % in this group of patients. A negative result of genetic screening for pathogenic variants in genes of the low-density lipoprotein receptor and its ligands does not rule out a diagnosis of familial hypercholesterolemia. In 20-40 % of cases, molecular genetic testing fails to detect changes in the above genes. The aim of this work was to search for new genes associated with the familial hypercholesterolemia phenotype by modern high-tech methods of sequencing and machine learning. On the basis of a group of patients with familial hypercholesterolemia (enrolled according to the Dutch Lipid Clinic Network Criteria and including cases confirmed by molecular genetic analysis), decision trees were constructed, which made it possible to identify cases in the study population that require additional molecular genetic analysis. Five probands were identified as having the severest familial hypercholesterolemia without pathogenic variants in the studied genes and were analyzed by whole-genome sequencing on the HiSeq 1500 platform (Illumina). The whole-genome sequencing revealed rare variants in three out of five analyzed patients: a heterozygous variant (rs760657350) located in a splicing acceptor site in the PLD1 gene (c.2430-1G>A), a previously undescribed single-nucleotide deletion in the SIDT1 gene [c.2426del (p.Leu809CysfsTer2)], new missense variant c.10313C>G (p.Pro3438Arg) in the LRP1B gene, and single-nucleotide deletion variant rs753876598 [c.165del (p.Ser56AlafsTer11)] in the CETP gene. All these variants were found for the first time in patients with a clinical diagnosis of familial hypercholesterolemia. Variants were identified that may influence the formation of the familial hypercholesterolemia phenotype.

LDLR gene’s promoter region hypermethylation in patients with familial hypercholesterolemia

Familial hypercholesterolemia (FH) is characterized by high low-density lipoprotein cholesterol (LDL-C) levels and a high risk of early coronary heart disease. Structural alterations in the LDLR, APOB, and PCSK9 genes were not found in 20–40% of patients diagnosed using the Dutch Lipid Clinic Network (DCLN) criteria. We hypothesized that methylation in canonical genes could explain the origin of the phenotype in these patients. This study included 62 DNA samples from patients with a clinical diagnosis of FH according to the DCLN criteria, who previously tested negative for structural alterations in the canonical genes, and 47 DNA samples from patients with normal blood lipids (control group). All DNA samples were tested for methylation in the CpG islands of the three genes. The prevalence of FH relative to each gene was determined in both groups and the respective prevalence ratios (PRs) were calculated. The methylation analysis of APOB and PCSK9 was negative in both groups, showing no relationship between methylation in these genes and the FH phenotype. As the LDLR gene has two CpG islands, we analyzed each island separately. The analysis of LDLR-island1 showed PR = 0.982 (CI 0.33–2.95; χ2 = 0.001; p = 0.973), also suggesting no relationship between methylation and the FH phenotype. Analysis of LDLR-island2 showed a PR of 4.12 (CI 1.43–11.88; χ2 = 13,921; p = 0.00019), indicating a possible association between methylation on this island and the FH phenotype.

P490 MANAGEMENT OF SEVERE HYPERCHOLESTEROLEMIA IN ITALY: EVIDENCE FROM SANTORINI STUDY

Abstract The management of severe hypercholesterolemia (sHC) (LDL–C &amp;gt;160 mg/dL) represents a clinical challenge in routine practice, mainly in the setting of high cardiovascular (CV) risk. The aim of the present analysis was to assess the characteristics and management at baseline examination of patients with sHC enrolled in the Italian cohort of SANTORINI study. The SANTORINI study (NCT04271280) is a multinational, observational, prospective study evaluating the use of lipid–lowering therapies (LLTs) in 9044 adult patients with high– and very–high CV risk enrolled from 14 European countries between March 2020 and February 2021, with a 12–month follow–up period per patient. The Italian cohort comprised 1977 patients, 229 (11.6%) of whom were classified with sHC. Their mean age was 59.4 years, 56% were male, BMI was 27.2 kg/m2 and mean LDL–C levels were 196.7 mg/dL. In 7% of cases sHC was reported to be associated with a clinical diagnosis of familial hypercholesterolemia. By investigators, 150 (65.5%) patients were classified at very–high and 79 (34.5%) at high CV risk, mainly (74.2%) based upon ESC/EAS European guidelines criteria. Atherosclerotic cardiovascular disease was actually present in 68.4% of patients, while 40.6% were on primary prevention. Despite sHC was associated with high CV risk, 64.6% of patients had no documented LLTs at baseline, 15.3% was receiving lipid–lowering monotherapy including 9.2% on statins (6.1 % moderate and 2.6% high–intensity), 1.7% were on ezetimibe, 1.6% on PCSK9i and 0.5% on other oral LLTs, and 20.1% was receiving combination therapy (10.9% were on statin + ezetimibe, 4.8% on PCSK9i + oral LLT, and 4.4% other oral combination therapy). Based on present findings, it is therefore concluded that, although the clinicians mostly follow current guidelines to determine CV risk in hypercholesterolemia, there is a low utilisation of LLTs, especially combination therapies, in the subgroup of patients with sHC at high and very–high CV risk. This means that further measures are needed to improve the therapeutic management of these patients in order to minimise the risk of adverse cardiovascular events.

Lipoprotein(a) Genotype Influences the Clinical Diagnosis of Familial Hypercholesterolemia.

Background Evidence suggests that LPA risk genotypes are a possible contributor to the clinical diagnosis of familial hypercholesterolemia (FH). This study aimed at determining the prevalence of LPA risk variants in adult individuals with FH enrolled in the Italian LIPIGEN (Lipid Transport Disorders Italian Genetic Network) study, with (FH/M+) or without (FH/M-) a causative genetic variant. Methods and Results An lp(a) [lipoprotein(a)] genetic score was calculated by summing the number risk-increasing alleles inherited at rs3798220 and rs10455872 variants. Overall, in the 4.6% of 1695 patients with clinically diagnosed FH, the phenotype was not explained by a monogenic or polygenic cause but by genotype associated with high lp(a) levels. Among 765 subjects with FH/M- and 930 subjects with FH/M+, 133 (17.4%) and 95 (10.2%) were characterized by 1 copy of either rs10455872 or rs3798220 or 2 copies of either rs10455872 or rs3798220 (lp(a) score ≥1). Subjects with FH/M- also had lower mean levels of pretreatment low-density lipoprotein cholesterol than individuals with FH/M+ (t test for difference in means between FH/M- and FH/M+ groups <0.0001); however, subjects with FH/M- and lp(a) score ≥1 had higher mean (SD) pretreatment low-density lipoprotein cholesterol levels (223.47 [50.40] mg/dL) compared with subjects with FH/M- and lp(a) score=0 (219.38 [54.54] mg/dL for), although not statistically significant. The adjustment of low-density lipoprotein cholesterol levels based on lp(a) concentration reduced from 68% to 42% the proportion of subjects with low-density lipoprotein cholesterol level ≥190 mg/dL (or from 68% to 50%, considering a more conservative formula). Conclusions Our study supports the importance of measuring lp(a) to perform the diagnosis of FH appropriately and to exclude that the observed phenotype is driven by elevated levels of lp(a) before performing the genetic test for FH.

A Family History of Hypercholesterolemia - the Role of Genetics

A Family History of Hypercholesterolemia - the Role of Genetics Abstract. Genetic testing is rarely used in Switzerland to confirm the clinical diagnosis of familial hypercholesterolemia. However, cascade genetic testing from an index case is recommended by the guidelines. By describing a patient and his family with severe hypercholesterolemia, we discuss the benefits, risks and barriers regarding the implementation of genetics for familial hypercholesterolemia. Family screening with genetic testing could become a standard of care for severe hypercholesterolemia.

Genetic testing for familial hypercholesterolemia in Quebec, Canada: a single-centre retrospective cohort study.

Familial hypercholesterolemia (FH) is associated with premature atherosclerotic cardiovascular disease caused by elevated low-density lipoprotein cholesterol (LDL-C) levels. We determined the impact of a full next-generation sequencing (NGS) genetic panel on reclassification of patients with a clinical diagnosis of FH in Quebec compared to the partial genetic panel currently offered by the Quebec Ministère de la Santé et des Services sociaux (Ministry of Health and Social Services) (MSSS), which includes 11 variants that are common in French Canadians. We conducted a retrospective cohort study in a subgroup of patients in the Canadian FH Registry seen at the McGill University Health Centre Preventive Cardiology/Lipid Clinic, Montréal, between September 2017 and September 2021 who were clinically diagnosed with severe hypercholesterolemia, probable FH or definite FH according to the Canadian definition of FH. Next-generation sequencing of the LDLR, APOB and PCSK9 genes, and multiplex ligation-dependent probe amplification of the LDLR gene to detect genetic variants, were performed. Among 335 consecutive patients with heterozygous FH (184 men [54.9%] and 151 women [45.1%]), the baseline LDL-C level was 6.96 (standard deviation 1.79) mmol/L. Patients identified through cascade screening were 11 years younger on average than index patients, and smaller proportions presented to the clinic with cardiovascular risk factors. A pathogenic FH variant was identified in 169 (73.8%) of the 229 patients who underwent genetic testing; the majority had variants in the LDLR (146 [86.4%]) or APOB (24 [14.2%]) gene. The genetic panel offered by the MSSS accounted for only 48% of the variants identified with the full NGS panel. Of the 229 patients, 90 (39.3%, 95% confidence interval 32.9%-46.0%) were reclassified from a clinical diagnosis of probable FH to definite FH after genetic screening with a full FH panel. Genetic testing in patients suspected of having FH provided diagnostic certainty and permitted many patients with a clinical diagnosis of probable FH to be reclassified as having definite FH. Genetic screening allows for increased identification of patients with FH and may therefore help reduce the burden of cardiovascular disease and mortality rates among Canadians with FH. Trial registration: ClinicalTrials.gov, no. NCT02009345.

Prevalence of premature coronary artery disease (CAD) according to clinical familial hypercholesterolaemia (FH) diagnosis in Lithuania

Background and Aims : We aimed to determine the prevalence of CAD according to clinical diagnosis of Familial Hypercholesterolemia(FH) in Lithuania.Methods: Prospective observational cohort study enrolled patients with clinically diagnosed FH treated in Vilnius University Hospital Santaros Klinikos during the period of 2016-2021. According to Dutch Lipid Clinic Network (DLCN) diagnostic criteria for FH, definite FH was diagnosed when a total point score was>8, probable–6-8, possible-3-5,unlikely<3 points. Premature CAD was defined as occuring in men <55 years and women <60 years. Obstructive Atherosclerotic CAD was defined as the presence of stenosis ≥50% in at least one coronary vessel in Coronary Computed Tomography Angiography(CCTA) or coronary angiography, as well as performed percutaneous coronary intervention(PCI) or coronary arteries bypass grafting(CABG). Data of 119 study patients were included in the analysis. The prevalence of premature CAD was compared in different groups according to FH diagnosis. Statistical analysis was performed using R(v. 4.0.4) program package.Results: Of 119 examined patients 52,1%(n=62) were women and47,9%(n=57) were men.In the study population, premature CAD was diagnosed for 26%(n=31) patients. 21,8%(n=26) of study patients had definite FH diagnosis, 37,8%(n=45) had probable FH, 28,6%(n=34) - possible FH and11,8% (n=14) had unlikely FH diagnosis. Premature CAD was diagnosed to 38,5%(n=10) patients with definite FH, 33,3%(n=15) with probable FH, 14,7%(n=5) with possible FH and 7,1%(n=1) among people with unlikely FH.Conclusions: Our findings indicate that among individuals with premature CAD there is an opportunity to detect an index case for initiation of cascade FH screening, especially in definite and probable FH cases. Background and Aims : We aimed to determine the prevalence of CAD according to clinical diagnosis of Familial Hypercholesterolemia(FH) in Lithuania. Methods: Prospective observational cohort study enrolled patients with clinically diagnosed FH treated in Vilnius University Hospital Santaros Klinikos during the period of 2016-2021. According to Dutch Lipid Clinic Network (DLCN) diagnostic criteria for FH, definite FH was diagnosed when a total point score was>8, probable–6-8, possible-3-5,unlikely<3 points. Premature CAD was defined as occuring in men <55 years and women <60 years. Obstructive Atherosclerotic CAD was defined as the presence of stenosis ≥50% in at least one coronary vessel in Coronary Computed Tomography Angiography(CCTA) or coronary angiography, as well as performed percutaneous coronary intervention(PCI) or coronary arteries bypass grafting(CABG). Data of 119 study patients were included in the analysis. The prevalence of premature CAD was compared in different groups according to FH diagnosis. Statistical analysis was performed using R(v. 4.0.4) program package. Results: Of 119 examined patients 52,1%(n=62) were women and47,9%(n=57) were men.In the study population, premature CAD was diagnosed for 26%(n=31) patients. 21,8%(n=26) of study patients had definite FH diagnosis, 37,8%(n=45) had probable FH, 28,6%(n=34) - possible FH and11,8% (n=14) had unlikely FH diagnosis. Premature CAD was diagnosed to 38,5%(n=10) patients with definite FH, 33,3%(n=15) with probable FH, 14,7%(n=5) with possible FH and 7,1%(n=1) among people with unlikely FH. Conclusions: Our findings indicate that among individuals with premature CAD there is an opportunity to detect an index case for initiation of cascade FH screening, especially in definite and probable FH cases.

DIstribution of overweight among men and women with clinical diagnosis of familial hypercholesterolaemia (FH) in Lithuania

DIstribution of overweight among men and women with clinical diagnosis of familial hypercholesterolaemia (FH) in Lithuania

Prevalence of obesity among men and women with clinical diagnosis of familial hypercholesterolaemia (FH) in Lithuania

Prevalence of obesity among men and women with clinical diagnosis of familial hypercholesterolaemia (FH) in Lithuania

Prevalence of premature atherosclerotic coronary artery disease (CAD) among men and women with familial hypercholesterolaemia (FH) in Lithuania

Background and Aims : According to various studies, coronary artery disease is the most prevalent type of cardiovascular disease amongFH patients. In our study we aimed to determine the distribution of premature CAD between men and women with clinical diagnosis of FH in Lithuania.

A Clinically Validated Genetic Screening for Familial Hypercholesterolemia in Quebec

Lead Author's Financial Disclosures Nothing to disclose. Study Funding None. Background/Synopsis Familial Hypercholesterolemia (FH) is the most common genetic disorder in humans with an estimated prevalence of 1/311. In geographic regions with founder effect mutations, such as the province of Quebec, Canada, prevalence is as high as 1/80. FH is associated with premature atherosclerotic cardiovascular disease (ASCVD) caused by elevated low-density lipoprotein cholesterol (LDL-C). Although early diagnosis and therapy of FH can normalize life expectancy, less than 15% of cases are diagnosed. Cascade screening and genetic testing aim to improve diagnosis, treatment, and outcomes in FH. Objective/Purpose Determine the impact of unbiased genetic testing in re-classification of patients with a clinical diagnosis of FH in Quebec, in comparison with the existing genetic panel offered by Quebec's Ministry of Health and Social Services (Ministere de la Sante et des Services Sociaux (MSSS)). Methods A retrospective cohort study was conducted on patients seen in the Preventive Cardiology/Lipid Clinic of the McGill University Health Center (MUHC) at the Royal Victoria Hospital in Montreal, Quebec, Canada, between September 2017 to September 2021. The MUHC Preventive Cardiology/Lipid clinic is one of the 19 academic FH Canada Registry participating sites. Here, we report a single-center experience with the only clinically validated molecular genetic screening for FH (CLIA compliant) in Canada. We performed next-generation sequencing of the LDLR, APOB, and PCSK9 genes and multiplex ligation-dependent probe amplification (MLPA) of the LDLR gene to detect genetic mutations and copy number variants. All mutations were reviewed by a geneticist and cross-referenced in ClinVar. Results Between 2018-2021, we examined 369 FH cases (57% males, 43% females) based on the Canadian FH definition clinical criteria. For index patients, mean age at diagnosis was 40+/- 16 years, while 30+/-16 years was for cascade screening patients. Baseline (untreated) LDL-C was 6.5+/-2.0 mmol/L. In 224 patients who underwent genetic testing, a pathogenic mutation was identified in 167 (75%) individuals, in keeping with ∼20% of FH patients with a polygenic form. A majority of affected patients had mutations in the LDLR (87%) or APOB (13%) genes. Interestingly, the genetic panel offered by Quebec's Health Ministry, which includes 10 common mutations in French Canadians, only accounted for 46% of identified mutations. Even in patients self-describing as French Canadians, more than 20% did not have a common mutation. We subsequently examined the impact of genetic testing in re-classification of patients' FH diagnosis. Interestingly, genetic screening identified a genetic variant in 26% of patients initially classified as 'severe hypercholesterolemia' and allowed for 85 (75%) of patients initially diagnosed as 'probable FH' to be re-classified as 'definite FH'. Conclusions Genetic testing in patients suspected of having FH provides diagnostic certainty and permits re-classification of individuals with a diagnosis of 'severe hypercholesterolemia' or 'probable FH' according to current definitions. Furthermore, the limited genetic panel offered by the province of Quebec, focusing on common French-Canadian mutations, provides incomplete data in the majority of cases. We therefore propose that most patients with a presumptive diagnosis of FH undergo an unbiased genetic analysis. This allows for increased identification of FH patients and can help reduce burden of ASCVD and death in Canadians with FH. Furthermore, this study has important implications on cascade screening, public health policies and reimbursement of drugs such as PCSK9 inhibitors. Nothing to disclose.

Identification and Functional Characterization of a Low-Density Lipoprotein Receptor Gene Pathogenic Variant in Familial Hypercholesterolemia.

We report a single-point variant of low-density lipoprotein receptor (LDLR) in a Chinese proband with a clinical diagnosis of familial hypercholesterolemia (FH) with a comprehensive functional analysis. Target exome capture-based next-generation sequencing was used for sequencing and identification of genomic variants in the LDLR gene. The expression, cellular location, and function of the mutant LDLR were analyzed. Sequencing of LDLR in FH patients indicated a point variant of single-base substitution (G < A) at a position of 2389 in the 16th exon, which led to a loss of the 16th exon in the LDLR messenger RNA. This genomic variant was found to cause exon 16 deletion in the mutant LDLR protein. Subsequent functional analyses showed that the mutant LDLR was retained in the Golgi apparatus and rarely expressed in the cellular membranes of HepG2 cells. Accordingly, the intake ability of HepG2 cells with the mutant LDLR was significantly reduced (P < 0.05). In conclusion, our results suggest that a mutant with a single-base substitution (c. 2389G > A) in the 16th exon of the LDLR gene was associated with miscleavage of messenger RNA and the retention of mutant LDLR in the Golgi apparatus, which revealed a pathogenic variant in LDLR underlying the pathogenesis of FH.

Measurement of Achilles Tendon Thickness is a Key for International Harmonization in Clinical Diagnosis of Familial Hypercholesterolemia.

Measurement of Achilles Tendon Thickness is a Key for International Harmonization in Clinical Diagnosis of Familial Hypercholesterolemia.

SCREENING FOR GENETIC MUTATIONS IN LDLR GENE WITH FAMILIAL HYPERCHOLESTEROLEMIA IN THE MONGOLIAN POPULATION

Abstract Objective: The objective of this study was to characterize LDLR (low density lipoprotein receptor) gene mutation in patients with familial hypercholesterolemia. Design and method: Methods: This cross-sectional study was included subjects aged from 20 to 64 years, with a clinical diagnosis of familial hypercholesterolemia. Clinical diagnosis of familial hypercholesterolemia was based on Dutch Lipid Clinic Network diagnostic criteria. Possible and probable familial hypercholesterolemia were defined as a total score was 3–5 and 6–8 points. Ten ml of venous blood samples were collected from all the subjects and used for biochemical and genetic analysis. Deoxyribonucleic acid was isolated from peripheral blood samples and precise primers were designed for LDLR gene which includes 18 exons. Polymerize chain reaction test was followed by deoxyribonucleic acid sequence analysis. Results: Results: A total of 89 subjects included in the study of which, 32 (36%) were men and 57 (64%) were women. The mean age of the participants was 46.5 ± 7.8 years. In our study, we found the following 3 LDLR mutations: S265R mutation in Exon-6, C308Y mutation Exon-8 and V502 M mutation in Exon-10. Conclusions: Conclusion: This was the first study to identify genetic mutations in LDLR gene in Mongolia. We conclude that screening of family hypercholesterolemia among the Mongolian population is very important to identify individuals who are prone to develop the atherosclerotic cardiovascular disease.

The Spectrum of Low-Density Lipoprotein Receptor Mutations in a Large Turkish Cohort of Patients with Familial Hypercholesterolemia.

Background: Monogenic hypercholesterolemia with Mendelian inheritance is a heterogeneous group of diseases that are characterized by elevated plasma low-density lipoprotein cholesterol (LDL-C) levels, and the most common form of this disorder is autosomal-dominant familial hypercholesterolemia (FH). Methods: A total of 104 index cases with the clinical diagnosis of FH were included in this study. Low-density lipoprotein receptor (LDLR) was sequenced using the Sanger sequencing method. Results: Pathogenic/likely pathogenic variants were detected in LDLR in 55 of the 104 cases (mutation detection rate = 52.8%). Thirty different variants were detected in LDLR, three of which were novel. The total cholesterol and LDL-C values of the patients in the group of premature termination codon (PTC) mutation carriers were significantly higher than those of the patients in the group of non-PTC mutation carriers. A total of 87 patients (17 pediatric and 70 adult cases) were diagnosed with cascade genetic screening. Statin treatment was recommended to all 87 patients and was accepted and initiated in 70 of these patients. Conclusions: This study is the largest patient cohort that evaluated FH cases in the Turkish population. Herein, we revealed the LDLR mutation spectrum for a Turkish population and compared the cases in the context of genotype-phenotype correlation. Genetic screening of individuals with suspected FH not only helps to establish their diagnosis, but also facilitates early diagnosis and treatment initiation in other family members through cascade screening.

Mutational Spectrum of LDLR and PCSK9 Genes Identified in Iranian Patients With Premature Coronary Artery Disease and Familial Hypercholesterolemia.

Familial hypercholesterolemia (FH) is a common, yet underdiagnosed, genetic disorder characterized by lifelong elevated low-density lipoprotein cholesterol levels, which can increase the risk of early-onset coronary artery disease (CAD). In the present study, we screened the nucleotide variations of the LDLR and PCSK9 genes, as well as a part of the APOB gene, in Iranian patients with FH and premature CAD to find the genetic cause of the disorder. Fifteen unrelated individuals with a clinical diagnosis of FH and premature CAD were recruited. Direct DNA sequencing was applied to screen the whole coding exons and exon–intron boundaries of the LDLR and PCSK9 genes and the main parts of their introns, together with exon 26 of the APOB gene. The pathogenicity of the identified mutations was investigated via either segregation analyses in the family or in silico predictive software. Six different point mutations (p.Cys148Tyr, p.Cys216Tyr, p.Cys302Trp, p.Cys338Trp, p.Leu479Gln, and p.G593Afs∗72) in LDLR and a double mutation (p.Asp172His and p.Ala53Val) in both LDLR and PCSK9 genes were identified in seven families with clinically diagnosed FH (43%), whereas no pathogenic mutations were found in eight families with clinically diagnosed FH. This study is the first to identify 1 pathogenic mutation in the LDLR gene (c.1014C > G [p.Cys338Trp]) and to cosegregate it from the affected individual in the family. No mutations were found in the APOB gene, whereas several silent mutations/polymorphisms were identified in the LDLR and PCSK9 genes. Genetic testing and reports on nucleotide alterations in the Iranian population are still limited. Our findings not only further confirm the significant role of FH in the incidence of premature CAD but also enlarge the spectrum of LDLR and PCSK9 variations and exhibit the heterogeneity of FH in Iranians. In patients with no mutation in the examined genes, the disease could be begotten either by a polygenic cause or by gene defects occurring in other related genes and regions not targeted in this study.

Genetically determined hypercholesterolaemia results into premature leucocyte telomere length shortening and reduced haematopoietic precursors

Leucocyte telomere length (LTL) shortening is a marker of cellular senescence and associates with increased risk of cardiovascular disease (CVD). A number of cardiovascular risk factors affect LTL, but the correlation between elevated LDL cholesterol (LDL-C) and shorter LTL is debated: in small cohorts including subjects with a clinical diagnosis of familial hypercholesterolaemia (FH). We assessed the relationship between LDL-C and LTL in subjects with genetic familial hypercholesterolaemia (HeFH) compared to those with clinically diagnosed, but not genetically confirmed FH (CD-FH), and normocholesterolaemic subjects. LTL was measured in mononuclear cells-derived genomic DNA from 206 hypercholesterolaemic subjects (135 HeFH and 71 CD-FH) and 272 controls. HeFH presented shorter LTL vs. controls (1.27 ± 0.07 vs. 1.59 ± 0.04, P = 0.045). In particular, we found shorter LTL in young HeFH as compared to young controls (<35 y) (1.34 ± 0.08 vs. 1.64 ± 0.08, P = 0.019); moreover, LTL was shorter in statin-naïve HeFH subjects as compared to controls (1.23 ± 0.08 vs. 1.58 ± 0.04, P = 0.001). HeFH subjects presented shorter LTL compared to LDL-C matched CD-FH (1.33 ± 0.05 vs. 1.55 ± 0.08, P = 0.029). Shorter LTL was confirmed in leucocytes of LDLR-KO vs. wild-type mice and associated with lower abundance of long-term haematopoietic stem and progenitor cells (LT-HSPCs) in the bone marrow. Accordingly, HeFH subjects presented lower circulating haematopoietic precursors (CD34 + CD45dim cells) vs. CD-FH and controls. We found (i) shorter LTL in genetically determined hypercholesterolaemia, (ii) lower circulating haematopoietic precursors in HeFH subjects, and reduced bone marrow resident LT-HSPCs in LDLR-KO mice. We support early cellular senescence and haematopoietic alterations in subjects with FH.

Abstract 13031: Universal Screening for Familial Hypercholesterolemia in Young Adults: The Young FH Study

Introduction: Familial hypercholesterolemia (FH) is caused by genetic defects in low-density lipoprotein (LDL) receptor pathway, resulting in a persistent elevation of plasma LDL-cholesterol (LDL-C) levels as well as an increased risk of cardiovascular diseases. Early diagnosis and treatment are imperative for its management. Currently, FH patients are mainly identified by cascade screening. However, FH is underdiagnosed and undertreated, particularly in young adults, which warrants a systematic screening strategy. Hypothesis: Considering that the prevalence of FH is high (~0.4% in the general population) and that treatment of FH should be initiated earlier at the latest in young adults, we hypothesized that the universal screening of LDL-C in young adults is beneficial for early diagnosis and treatment of FH. Methods: At the University of Tokyo, plasma LDL-C levels have been measured at heath checkups for employees as well as new students. Young adults (18-30 years old) with hypercholesterolemia (LDL-C ≥ 160 mg/dL) identified by universal screening and referred to the University of Tokyo Hospital were eligible (the Young FH study). Those who have been identified by cascade screening were excluded. Mutation in FH-causing genes, as well as clinical and biochemical parameters useful for the clinical diagnosis of FH, were analyzed. The protocol was approved by the human genome, gene analysis research ethics committee of the University of Tokyo. Results: Of the total participants (n = 89, mean age 23.4 ± 3.4 years), 36 (40%) had mutations in LDLR or PCSK9 . The prevalence of mutation carriers was higher in non-obese than in obese participants (47% for body mass index (BMI) &lt; 24 kg/m 2 vs. 26% for BMI ≥ 24). The sensitivity and specificity of clinical diagnosis were 28% and 85%, respectively, by Dutch Lipid Clinic Network Criteria (definite + probable FH), or 22% and 98%, respectively, by Japanese diagnostic criteria of FH. Conclusions: The universal screening of LDL-C effectively identifies FH high-risk patients in Japanese young adults. This screening may be beneficial in countries with low-prevalence of obesity or in non-obese populations. The use of clinical diagnostic criteria of FH for universal screening may lead to underdiagnosis.