Mutant Apo Research Articles

Evaluation of biochemical algorithms to screen dysbetalipoproteinemia and ApoE mutations

Evaluation of biochemical algorithms to screen dysbetalipoproteinemia and ApoE mutations

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.

Cognitive Decline: Current Intervention Strategies and Integrative Therapeutic Approaches for Alzheimer's Disease.

Alzheimer's disease (AD) represents a pressing global health challenge, with an anticipated surge in diagnoses over the next two decades. This progressive neurodegenerative disorder unfolds gradually, with observable symptoms emerging after two decades of imperceptible brain changes. While traditional therapeutic approaches, such as medication and cognitive therapy, remain standard in AD management, their limitations prompt exploration into novel integrative therapeutic approaches. Recent advancements in AD research focus on entraining gamma waves through innovative methods, such as light flickering and electromagnetic fields (EMF) stimulation. Flickering light stimulation (FLS) at 40 Hz has demonstrated significant reductions in AD pathologies in both mice and humans, providing improved cognitive functioning. Additionally, recent experiments have demonstrated that APOE mutations in mouse models substantially reduce tau pathologies, with microglial modulation playing a crucial role. EMFs have also been demonstrated to modulate microglia. The exploration of EMFs as a therapeutic approach is gaining significance, as many recent studies have showcased their potential to influence microglial responses. Th article concludes by speculating on the future directions of AD research, emphasizing the importance of ongoing efforts in understanding the complexities of AD pathogenesis through a holistic approach and developing interventions that hold promise for improved patient outcomes.

IPSC-derived PSEN2 (N141I) astrocytes and microglia exhibit a primed inflammatory phenotype

BackgroundWidescale evidence points to the involvement of glia and immune pathways in the progression of Alzheimer’s disease (AD). AD-associated iPSC-derived glial cells show a diverse range of AD-related phenotypic states encompassing cytokine/chemokine release, phagocytosis and morphological profiles, but to date studies are limited to cells derived from PSEN1, APOE and APP mutations or sporadic patients. The aim of the current study was to successfully differentiate iPSC-derived microglia and astrocytes from patients harbouring an AD-causative PSEN2 (N141I) mutation and characterise the inflammatory and morphological profile of these cells.MethodsiPSCs from three healthy control individuals and three familial AD patients harbouring a heterozygous PSEN2 (N141I) mutation were used to derive astrocytes and microglia-like cells and cell identity and morphology were characterised through immunofluorescent microscopy. Cellular characterisation involved the stimulation of these cells by LPS and Aβ42 and analysis of cytokine/chemokine release was conducted through ELISAs and multi-cytokine arrays. The phagocytic capacity of these cells was then indexed by the uptake of fluorescently-labelled fibrillar Aβ42.ResultsAD-derived astrocytes and microglia-like cells exhibited an atrophied and less complex morphological appearance than healthy controls. AD-derived astrocytes showed increased basal expression of GFAP, S100β and increased secretion and phagocytosis of Aβ42 while AD-derived microglia-like cells showed decreased IL-8 secretion compared to healthy controls. Upon immunological challenge AD-derived astrocytes and microglia-like cells showed exaggerated secretion of the pro-inflammatory IL-6, CXCL1, ICAM-1 and IL-8 from astrocytes and IL-18 and MIF from microglia.ConclusionOur study showed, for the first time, the differentiation and characterisation of iPSC-derived astrocytes and microglia-like cells harbouring a PSEN2 (N141I) mutation. PSEN2 (N141I)-mutant astrocytes and microglia-like cells presented with a ‘primed’ phenotype characterised by reduced morphological complexity, exaggerated pro-inflammatory cytokine secretion and altered Aβ42 production and phagocytosis.

Neuronal lipid metabolism genetics and Early‐Onset Alzheimer’s Disease: A systematic review and meta‐analysis of observational studies

AbstractBackgroundEarly Onset Alzheimer’s disease (EOAD) is associated with mutations in APP, PSEN1 and PSEN 2 genes but few studies have assessed its relationship with mutations involved in lipid metabolism and the amyloid cascade. Therefore, this study seeks to determine the association of ABCA7, SORL1 and APOE mutations with EOAD.MethodThe protocol was registered in PROSPERO(CRD42022328366). We included comparative observational studies assessing the association of ABCA7, SORL1 and APOE mutations with the development of EOAD in patients younger than 65 years old. The search strategy was performed in five databases (MEDLINE, Scopus, Web of Science, EMBASE, Opengray) from their inception to May 7th,2022. Abstract and full‐text screening, data extraction and risk of bias (RoB) assessment were performed in duplicates. RoB was assessed with Newcastle‐Ottawa Scale. We performed a random effects meta‐analysis for dichotomous outcomes by using the DerSimoniain Laird method. Effect sizes were reported as odds ratio (OR) with their corresponding 95% confidence intervals (95%CI).ResultA total of 2191 studies were screened and seven studies (n = 8992) were included; one was a retrospective cohort and six were case‐control studies. Three studies had high RoB and four had low RoB. Overall, 60% were female and the mean age ranged from 33.9(SD±17.1) to 57.4(SD±5.6). Three case‐control studies (n = 5098) found a significant association of ABCA7 mutation with EOAD (OR:2.51 95%CI[1.33‐4.73]; tau‐squared = 0.20, I‐squared = 66%). Two case‐control studies (n = 3107) found that SORL1 mutation was not associated with EOAD (OR:3.65 95%CI[0.76‐17.49]; tau‐squared = 1.15, I‐squared = 89%). Two case‐control studies and one cohort study (n = 787) found that APOE4 allelic variant mutation of the APOE gene had significant association with EOAD (OR:13.21; 95%CI[3.81‐45.85]; tau‐squared = 0.90, I‐squared = 75%) and that the APOE2 allelic variant mutation was not associated with EOAD.ConclusionDespite the high heterogeneity in our results and limited number of studies, this study shows that ABCA7 and APOE mutations may be associated with an increased risk of EOAD. Larger high‐quality cohort studies are needed to address this research question.

An optimized method for PCR-based genotyping to detect human APOE polymorphisms

BackgroundApolipoprotein E (APOE) is one of the most polymorphic genes at two single nucleotides (rs429358 and rs7412). The various isoforms of APOE have been associated with a variety of diseases, including neurodegenerative, type 2 diabetes, etc. Hence, predicting the APOE genotyping is critical for disease risk evaluation. The purpose of this study was to optimize the tetra amplification refractory mutation system (Tetra-ARMS) PCR method for the detection of APOE mutations. Material and methodsHere, in our optimized Tetra-ARMS PCR method, different factors like cycle conditions, using HiFidelity enzyme instead of Taq polymerase and setting its best concentration, and the lack of using dimethylsulfoxide (DMSO) for amplifying the GC-regions were set up for all primer pairs. The sensitivity and accuracy were tested. For validation of the assay, the results were compared with known genotypes for the APOE gene that were previously obtained by two independent methods, RFLP and Chip-typing. ResultsSuccessful Tetra-ARMS PCR and genotyping are influenced by multiple factors. Our developed method enabled us to amplify the DNA fragment by 25 cycles without adding any hazardous reagent, like DMSO. Our findings showed 100 % accuracy and sensitivity of the optimized Tetra-ARMS PCR while both criteria were 95 % for RFLP and 100 % for the chip-typing method. In addition, our results showed 91 % and 100 % consistency with RFLP and chip typing methods, respectively. ConclusionsOur current method is a simple and accurate approach for detecting APOE polymorphisms within a large sample size in a short time and can be performed even in low-tech laboratories.

The Apolipoprotein E neutralizing antibody inhibits SARS-CoV-2 infection by blocking cellular entry of lipoviral particles.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causal agent for coronavirus disease 2019 (COVID-19). Although vaccines have helped to prevent uncontrolled viral spreading, our understanding of the fundamental biology of SARS-CoV-2 infection remains insufficient, which hinders effective therapeutic development. Here, we found that Apolipoprotein E (ApoE), a lipid binding protein, is hijacked by SARS-CoV-2 for infection. Preincubation of SARS-CoV-2 with a neutralizing antibody specific to ApoE led to inhibition of SARS-CoV-2 infection. The ApoE neutralizing antibody efficiently blocked SARS-CoV-2 infection of human iPSC-derived astrocytes and air-liquid interface organoid models in addition to human ACE2-expressing HEK293T cells and Calu-3 lung cells. ApoE mediates SARS-CoV-2 entry through binding to its cellular receptors such as the low density lipoprotein receptor (LDLR). LDLR knockout or ApoE mutations at the receptor binding domain or an ApoE mimetic peptide reduced SARS-CoV-2 infection. Furthermore, we detected strong membrane LDLR expression on SARS-CoV-2 Spike-positive cells in human lung tissues, whereas no or low ACE2 expression was detected. This study provides a new paradigm for SARS-CoV-2 cellular entry through binding of ApoE on the lipoviral particles to host cell receptor(s). Moreover, this study suggests that ApoE neutralizing antibodies are promising antiviral therapies for COVID-19 by blocking entry of both parental virus and variants of concern.

Novel APOE Mutation in a Moroccan Subject Suffering from Alzheimer Disease: A Case Study and Exploration of Pathogenic Implication.

Alzheimer disease (AD) is a major public health concern worldwide. It is a severe neurodegenerative disease that primarily affects the elderly and causes significant brain cell death. According to the most complete scientific research, the APOE gene, which encodes the APOE protein, maybe the key to identifying the likely cause of delayed AD. The development of plaques and tangles, as well as increased amyloid (amyloid-β) levels and deposition, have been linked to APOE4. Pathogenic mutations in this gene can impact how beta-amyloid deposits and how they are cleared from the body. In this study, we report a novel pathogenic mutation, Arg160Leu, in APOE that was identified in a Moroccan patient. The magnetic resonance imaging of this 67-year-old woman revealed hippocampal shrinkage, and the results of her cognition testing revealed that she is suffering from severe AD. The current study may increase awareness of the genetic risk factors for AD caused by APOE4 mutations.

Clinical and genetic variants of hypertriglyceridemia in the practice of a lipidologist

Background. An important role in identifying the causes and determining the prognostic significance of dyslipidemia belongs to the level of triglycerides. High triglycerides are a risk factor for the development or early onset of cardiovascular disease.
 Aim. To assess the frequency of detection and causes of hypertriglyceridemia among patients receiving outpatient appointments with a lipidologist.
 Material and methods. An analysis of lipid metabolism disorders in patients of the Adult Lipidology Center was carried out: 1233 people aged 1884 years, including 777 (63%) women and 456 (37%) men. Examination of patients with dyslipidemia included an examination by a cardiologist-lipidologist (with the calculation of the risk of cardiovascular complications), an assessment of the probability of familial hypercholesterolemia according to the British scale and the criteria of the Dutch lipid clinics, a biochemical blood test, an analysis of the thyroid status, the content of glycated hemoglobin, extracranial duplex scanning, according to indications echocardiography. Biomaterial samples from 421 patients with the phenotype of inherited dyslipidemia were examined by next generation sequencing to identify the carriage of APOE gene isoforms, as well as genes associated with familial hypercholesterolemia (LDLR, LDLRAP1, APOB, PCSK9). For statistical processing of research data, descriptive statistics methods were used. In a non-parametric distribution, data were expressed as Me (Q1; Q3). When performing statistical processing of the obtained data, nonparametric tests (MannWhitney test, when comparing qualitative data 2 and Fisher's exact test, odds ratio and relative risk) were used. The value of p 0.05 was taken as a criterion of significance. The nature of the data distribution was assessed using the KolmogorovSmirnov test.
 Results. Elevated triglyceride levels were detected in 341 (27.66%) patients: 220 (64.5%) women and 121 (35.5%) men. Mild degree of hypertriglyceridemia occured in 42.5% of cases, moderate in 42.5%, severe in 7.6%, extremely severe in 7.4%. The genetic characteristics of patients with hypertriglyceridemia were determined, and 1 previously undescribed variant of the APOE mutation was found.
 Conclusion. The most common forms of hypertriglyceridemia were mild and moderate, the most common variants of APOE mutations were p.Cys130Arg and p.Arg176Cys.

Genetic Variants Associated with Severe Hypertriglyceridemia: LPL, APOC2, APOA5, GPIHBP1, LMF1, and APOE.

High triglyceride (TG) levels are associated with an increased risk for atherosclerotic cardiovascular disease (ASCVD) and pancreatitis. The objectives for this study were to evaluate for the coexistence of severe HTG and pancreatitis in two different geographic regions of Turkey and to identify rare variants that cause monogenic HTG in our country. In our study from 2014 to 2019, patients with severe HTG who presented to the endocrinology outpatient clinics with TG levels >500 mg/dL (5.7 mmol/L) were evaluated. The LPL, APOC2, APOA5, GPIHBP1, LMF1, and APOE genes were sequenced using next generation sequencing to screen for potentially pathogenic variants. Potentially pathogenic variants were identified in 64 (47.1%) of 136 patients. Variants in LPL were seen in 42 (30.9%) cases, APOA5 variants in 10 (7.4%) cases, APOC2 variants in 5 (3.7%) cases, LMF1 variants in 5 (3.7%) cases, and APOE mutations in 2 (1.5%) cases. In the subgroup that experienced pancreatitis (n = 76, 56.3%), LPL variants were seen at higher frequency (P <0.001) than in the subgroup with no history of pancreatitis (n = 60, 43.7%). Patients who developed pancreatitis (56.3%) demonstrated a median TG of 2083 mg/dL (23.5 mmol/L), and patients without pancreatitis (43.7%) demonstrated a median TG of 1244.5 mg/dL (14.1 mmol/L) (P <0.001). Accurate approach to HTG diagnosis is important for the prevention of pancreatitis and ASCVD. Evaluation of variants in primary HTG after excluding secondary causes may help provide a patient-centric precision treatment plan.

A molecular classification of gastric cancer associated with distinct clinical outcomes and validated by an XGBoost-based prediction model

Gastric cancer (GC) is a heterogeneous disease and a leading cause of cancer-related deaths. Discovering robust, clinically relevant molecular classifications is critical for guiding personalized therapies for GC. Here, we propose a refined molecular classification scheme for GC using integrated optimal algorithms and multi-omics data. Based on the important features of mRNA, microRNA, and DNA methylation data selected by the multivariate Cox regression model, three subtypes linked to distinct clinical outcomes were identified by combining similarity network fusion and consensus clustering methods. Three subtypes were validated by an extreme gradient boosting machine learning prediction model with 125 differentially expressed genes in multiple independent cohorts. The molecular characteristics of mutation signatures, characteristic gene sets, driver genes, and chemotherapy sensitivity for each subtype were also identified: subtype 1 was associated with favorable prognosis and characterized by high ARID1A and PIK3CA mutations, subtype 2 was associated with a poor prognosis and harbored high recurrent TP53 mutations, and subtype 3 was associated with high CHD1, APOA1 mutations, and a poor prognosis. The proposed three-subtype scheme achieved a better clinical prediction performance (area under the curve value= 0.71) than The Cancer Genome Atlas classification, which may provide a practical subtyping framework to improve the treatment of GC.

Analysis of the difference in SLCO1B1 and APOE gene polymorphisms between Mongolian and Han populations.

Objective: To analyze SLCO1B1 and APOE polymorphisms and their clinical significance in the Mongolian and Han populations in Ordos, Inner Mongolia. Methods: Mongolian patients (n = 200)with cardiovascular disease admitted to our hospital from January 2018 to December 2020 were selected as the Mongolian population group. Han patients (n = 200) with cardiovascular diseases admitted during the same period were selected as the Han population group. Mutations in SLCO1B1 and APOE were detected by real-time fluorescence qPCR, and the differences between the two groups were analyzed. Results: The nucleotide polymorphisms of SLCO1B1 and APOE in the Mongolian and Han populations were consistent with the Hardy-Weinberg law. There were significant differences in gender, age, BMI, hypertension, alcohol consumption, dyslipidemia and low-density lipoprotein cholesterol levels between the two groups. APOE genotypes were classified according to those related to the efficacy of statins and the risk of atherosclerosis, and there was a significant difference between the two groups. Conclusion: There were differences in SLCO1B1 and APOE polymorphisms between the Mongolian and Han populations in Ordos. These may explain the differences in the incidence of cardiovascular diseases and the lipid-lowering efficacy of statins between the two populations.

Endothelial Cells Induced Progenitors Into Brown Fat to Reduce Atherosclerosis.

Insulin resistance (IR) can increase atherosclerotic and cardiovascular risk by inducing endothelial dysfunction, decreasing nitric oxide (NO) production, and accelerating arterial inflammation. The aim is to determine the mechanism by which insulin action and NO production in endothelial cells can improve systemic bioenergetics and decrease atherosclerosis via differentiation of perivascular progenitor cells (PPCs) into brown adipocytes (BAT). Studies used various endothelial transgenic and deletion mutant ApoE-/- mice of insulin receptors, eNOS (endothelial NO synthase) and ETBR (endothelin receptor type B) receptors for assessments of atherosclerosis. Cells were isolated from perivascular fat and micro-vessels for studies on differentiation and signaling mechanisms in responses to NO, insulin, and lipokines from BAT. Enhancing insulin's actions on endothelial cells and NO production in ECIRS1 transgenic mice reduced body weight and increased systemic energy expenditure and BAT mass and activity by inducing differentiation of PPCs into beige/BAT even with high-fat diet. However, positive changes in bioenergetics, BAT differentiation from PPCs and weight loss were inhibited by N(gamma)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of eNOS, in ECIRS1 mice and eNOSKO mice. The mechanism mediating NO's action on PPC differentiation into BAT was identified as the activation of solubilized guanylate cyclase/PKGIα (cGMP protein-dependent kinase Iα)/GSK3β (glycogen synthase kinase 3β) pathways. Plasma lipidomics from ECIRS1 mice with NO-induced increased BAT mass revealed elevated 12,13-diHOME production. Infusion of 12,13-diHOME improved endothelial dysfunction and decreased atherosclerosis, whereas its reduction had opposite effects in ApoE-/-mice. Activation of eNOS and endothelial cells by insulin enhanced the differentiation of PPC to BAT and its lipokines and improved systemic bioenergetics and atherosclerosis, suggesting that endothelial dysfunction is a major contributor of energy disequilibrium in obesity.

P286 ECHOCARDIOGRAPHIC FINDINGS IN SUBJECTS WITH AN AMYLOIDOGENIC APOLIPOPROTEIN A1 MUTATION

Abstract Background The APOA1 gene encodes the precursor of apolipoprotein AI (ApoAI), whose mature form is the major component of high–density lipoproteins. APOA1 mutations may cause a form of hereditary amyloidosis (AApoAI). Only very small case series of patients with AApoAI are available. Methods We examined 189 consecutive subjects with the heterozygous APOA1 Leu75Pro mutation referred for cardiac screening over a 10–year timespan at the Spedali Civili of Brescia (Italy). Results Subjects (men 54%, median age 55 years, renal disease 39%, liver disease 31%) had a median left ventricular ejection fraction (LVEF) of 60% (55–66), did not display a prominent diastolic dysfunction (E/e’ ratio 7 [6–10]) nor LV hypertrophy (LV mass index [LVMI] 92 g/m2 [74–111]). LV global longitudinal strain (GLS) (–19% [–21 to –17]), and mass to strain ratio (MSR) (10.0 [6.8–12.1]) were within normal limits. Age correlated with several echocardiographic parameters, including interventricular septal (IVS) thickness (r = 0.484), LVMI (r = 0.459), E/e’ (r = 0.501), and right ventricular free wall thickness (r = 0.459) (all p &amp;lt; 0.001). Some individuals displayed echocardiographic red flags of cardiac amyloidosis (CA; “granular sparkling” of the IVS, 19%; pericardial effusion, 11%; apical sparing, 10%; thickened atrioventricular valves, 8%). Thirteen out of 96 (14%) fulfilled non–invasive criteria for CA. Twenty–nine subjects died over 5.8 years (4.1–8.0), with 10 deaths for cardiovascular causes; 14 out of 182 (8%) were hospitalized because of HF, and 17 (9%) died for cardiovascular causes or were hospitalized for HF. Individuals with suspected CA had a much higher risk of all–cause death (p = 0.009), cardiovascular death (p &amp;lt; 0.001), cardiovascular death or HF hospitalization (p &amp;lt; 0.001), and HF hospitalization alone (p &amp;lt; 0.001). Furthermore, subjects with either renal or liver involvement had a higher risk of events and a worse outcome. Conclusions In subjects with an amyloidogenic APOA1 mutation, transthoracic echocardiography showed only minor signs of cardiac disease. The correlations between age and echocardiographic findings suggested a progressive increase in wall thickness, a decline in systolic and diastolic function, and a greater uncoupling between LV mass and contractility over time. Subjects with both renal and liver disease displayed the most evident signs of biventricular involvement and had a worse outcome.

An Updated Review and Meta Analysis of Lipoprotein Glomerulopathy.

More than 200 cases of lipoprotein glomerulopathy (LPG) have been reported since it was first discovered 30 years ago. Although relatively rare, LPG is clinically an important cause of nephrotic syndrome and end-stage renal disease. Mutations in the APOE gene are the leading cause of LPG. APOE mutations are an important determinant of lipid profiles and cardiovascular health in the population and can precipitate dysbetalipoproteinemia and glomerulopathy. Apolipoprotein E-related glomerular disorders include APOE2 homozygote glomerulopathy and LPG with heterozygous APOE mutations. In recent years, there has been a rapid increase in the number of LPG case reports and some progress in research into the mechanism and animal models of LPG. We consequently need to update recent epidemiological studies and the molecular mechanisms of LPG. This endeavor may help us not only to diagnose and treat LPG in a more personized manner but also to better understand the potential relationship between lipids and the kidney.

The experience of hereditary apolipoprotein A-I amyloidosis at the UK National Amyloidosis Centre

Introduction Hereditary apolipoprotein A-I (AApoAI) amyloidosis is a rare heterogeneous disease with variable age of onset and organ involvement. There are few series detailing the natural history and outcomes of solid organ transplantation across a range of causative APOA1 gene mutations. Methods We identified all patients with AApoAI amyloidosis who presented to the National Amyloidosis Centre (NAC) between 1986 and 2019. Results In total, 57 patients with 14 different APOA1 mutations were identified including 18 patients who underwent renal transplantation (5 combined liver-kidney (LKT) and 2 combined heart-kidney (HKT) transplants). Median age of presentation was 43 years and median time from presentation to referral was 3 (0–31 years). Involvement of the kidneys, liver and heart by amyloid was detected in 81%, 67% and 28% of patients, respectively. Renal amyloidosis was universal in association with the most commonly identified variant (Gly26Arg, n = 28). Across all variants, patients with renal amyloidosis had a median creatinine of 159 µmol/L and median urinary protein of 0.3 g/24 h at the time of diagnosis of AApoAI amyloidosis and median time from diagnosis to end-stage renal disease was 15.0 (95% CI: 10.0–20.0) years. Post-renal transplantation, median allograft survival was 22.0 (13.0–31.0) years. There was one early death following transplantation (infection-related at 2 months post-renal transplant) and no episodes of early rejection leading to graft failure. Liver transplantation led to regression of amyloid in all four cases in whom serial 123I-SAP scintigraphy was performed. Conclusions AApoAI amyloidosis is a slowly progressive disease that is challenging to diagnose. The outcomes of transplantation are encouraging and graft survival is excellent.

LDL-C Concentrations and the 12-SNP LDL-C Score for Polygenic Hypercholesterolaemia in Self-Reported South Asian, Black and Caribbean Participants of the UK Biobank.

Background: Monogenic familial hypercholesterolaemia (FH) is an autosomal dominant disorder characterised by elevated low-density lipoprotein cholesterol (LDL-C) concentrations due to monogenic mutations in LDLR, APOB, PCSK9, and APOE. Some mutation-negative patients have a polygenic cause for elevated LDL-C due to a burden of common LDL-C-raising alleles, as demonstrated in people of White British (WB) ancestry using a 12-single nucleotide polymorphism (SNP) score. This score has yet to be evaluated in people of South Asian (SA), and Black and Caribbean (BC) ethnicities. Objectives: 1) Compare the LDL-C and 12-SNP score distributions across the three major ethnic groups in the United Kingdom: WB, SA, and BC individuals; 2) compare the association of the 12-SNP score with LDL-C in these groups; 3) evaluate ethnicity-specific and WB 12-SNP score decile cut-off values, applied to SA and BC ethnicities, in predicting LDL-C concentrations and hypercholesterolaemia (LDL-C>4.9 mmol/L). Methods: The United Kingdom Biobank cohort was used to analyse the LDL-C (adjusted for statin use) and 12-SNP score distributions in self-reported WB (n = 353,166), SA (n = 7,016), and BC (n = 7,082) participants. To evaluate WB and ethnicity-specific 12-SNP score deciles, the total dataset was split 50:50 into a training and testing dataset. Regression analyses (logistic and linear) were used to analyse hypercholesterolaemia (LDL-C>4.9 mmol/L) and LDL-C. Findings: The mean (±SD) measured LDL-C differed significantly between the ethnic groups and was highest in WB [3.73 (±0.85) mmol/L], followed by SA [3.57 (±0.86) mmol/L, p < 2.2 × 10−16], and BC [3.42 (±0.90) mmol/L] participants (p < 2.2 × 10−16). There were significant differences in the mean (±SD) 12-SNP score between WB [0.90 (±0.23)] and BC [0.72 (±0.25), p < 2.2 × 10−16], and WB and SA participants [0.86 (±0.19), p < 2.2 × 10−16]. In all three ethnic groups the 12-SNP score was associated with measured LDL-C [R 2 (95% CI): WB = 0.067 (0.065–0.069), BC = 0.080 (0.063–0.097), SA = 0.027 (0.016–0.038)]. The odds ratio and the area under the curve for hypercholesterolaemia were not statistically different when applying ethnicity-specific or WB deciles in all ethnic groups. Interpretation: We provide information on the differences in LDL-C and the 12-SNP score distributions in self-reported WB, SA, and BC individuals of the United Kingdom Biobank. We report the association between the 12-SNP score and LDL-C in these ethnic groups. We evaluate the performance of ethnicity-specific and WB 12-SNP score deciles in predicting LDL-C and hypercholesterolaemia.

Mutation analysis of disease causing genes in patients with early onset or familial forms of Alzheimer\u2019s disease and frontotemporal dementia

BackgroundMost dementia disorders have a clear genetic background and a number of disease genes have been identified. Mutations in the tau gene (MAPT) lead to frontotemporal dementia (FTD), whereas mutations in the genes for the amyloid-β precursor protein (APP) and the presenilins (PSEN1, PSEN2) cause early-onset, dominantly inherited forms of Alzheimer’s disease (AD).Even if mutations causing Mendelian forms of these diseases are uncommon, elucidation of the pathogenic effects of such mutations have proven important for understanding the pathogenic processes. Here, we performed a screen to identify novel pathogenic mutations in known disease genes among patients undergoing dementia investigation.ResultsUsing targeted exome sequencing we have screened all coding exons in eleven known dementia genes (PSEN1, PSEN2, APP, MAPT, APOE, GRN, TARDBP, CHMP2B, TREM2, VCP and FUS) in 102 patients with AD, FTD, other dementia diagnoses or mild cognitive impairment.We found three AD patients with two previously identified pathogenic mutations in PSEN1 (Pro264Leu and Met146Val). In this screen, we also identified the recently reported APP mutation in two siblings with AD. This mutation, named the Uppsala mutation, consists of a six amino acid intra-amyloid β deletion.In addition, we found several potentially pathogenic mutations in PSEN2, FUS, MAPT, GRN and APOE. Finally, APOE ε4 was prevalent in this patient group with an allele frequency of 54%.ConclusionsAmong the 102 screened patients, we found two disease causing mutations in PSEN1 and one in APP, as well as several potentially pathogenic mutations in other genes related to neurodegenerative disorders. Apart from giving important information to the clinical investigation, the identification of disease mutations can contribute to an increased understanding of disease mechanisms.

Familial Hypercholesterolemia Due to APOE p.Leu167del Mutation, Response to Bempedoic Acid/Ezetimibe, after Failure of Both Inclisiran and Evolocumab, in a Statin Intolerant Patient: A Case Report

<h3>Lead Author's Financial Disclosures</h3> M.D. has received speaker's bureau honorarium from Amgen and Esperion and for advisory board honorarium from The Medicines Company. <h3>Study Funding</h3> None. <h3>Background/Synopsis</h3> Both inclisiran and evolocumab have been shown to reduce LDL-C in patients with heterozygous FH. Occasional cases of nonresponse have been reported. A rare genetic form of HeFH exhibits LDL-C nonresponse to both inclisiran and evolocumab, but a robust response to bempedoic acid/ezetimibe. <h3>Objective/Purpose</h3> To describe LDL-C responses to inclisiran, evolocumab, and bempedoic acid/ezetimibe, in a patient with HeFH due the APOE p.Leu167del mutation. <h3>Methods</h3> A participant in the Orion 10 clinical trial dropped from the Open Label Extension study because of lack of inclisiran efficacy. Genetic testing was obtained. For management of his lipid disorder, the patient was treated first with evolocumab and then with bempedoic acid/ezetimibe. <h3>Results</h3> A 63-year-old statin intolerant male with definite HeFH by the Dutch Criteria, and premature ASCVD manifested by an MI at age 47 followed by multiple PCIs (12 stents), dropped from the Open Label Extension of Orion 10 for nonresponse. His baseline LDL-C at randomization had been 178 mg/dL, while his on treatment (inclisiran 300 mg every 6 months) LDL-C was 204 mg/dL, representing a 13% increase. New baseline LDL-C was 202 mg/dL when evolocumab 140 mg every 2 weeks was added. After 5 weeks, LDL-C was 195 mg/dL, a 3% decrease, and after 8 weeks, LDL-C was 190 mg/dL, a 6% decrease. Evolocumab was stopped for nonresponse. A GBinsight Comprehensive Dyslipidemia panel identified neither pathogenic nor likely pathogenic variants in the LDLR, APOB, PCSK9, or RAP1 genes, but did demonstrate that the patient is heterozygous for a very rare variant in his APOE gene, c.500_502del(p.Leu167del). Next, bempedoic acid 180 mg/ezetimibe 10 mg daily was added. 6 weeks later, LDL-C was 63 mg/dL, down from 190 mg/dL, a decrease of 67%. <h3>Conclusions</h3> This patient with HeFH due to the APOE p.Leu167del mutation exhibited nonresponse to the PCSK9-reducing drugs, inclisiran, and evolocumab. The response to bempedoic acid/ezetimibe, however, was robust. In the homozygous state, this APOE variant causes the rare disease, Sea-Blue Histiocyte Syndrome, and in the heterozygous state, this variant is a rare cause of HeFH. The reported mechanism is that VLDL carrying the mutant apo E produces LDLR down-regulation in hepatocytes, thereby raising plasma LDL-C. Subjects with the APOE p.Leu167del mutation are reported to have a higher lipid-lowering response to statins than HeFH due to LDLR mutations. In this statin intolerant patient, bempedoic acid/ezetimibe produced a similar, heightened LDL-C-lowering response.

Identification of a novel APOE mutation in one Korean male patient.

A novel APOE mutation with Leucine-to-Proline exchange was identified in a 54-year-old Korean male patient predominantly suffering with Early Onset Alzheimer's Disease. Whole exome sequencing of the patient's DNA revealed a novel Leucine to Proline exchange of this mutation in the APOE gene. It was verified using Sanger Sequencing. It is a heterozygous ε3/ε3 T>C exchange. Protein 3D structure was created using Discovery Studio. The variant was checked in the reference databases including KRGDB, 1000Genome for its uniqueness. The mutation was screened by SIFT (Sorting Intolerant From Tolerant) and PolyPhen-2 for its pathogenicity. APOE Leu>Pro exchange could disturb the helix-4 structure of the APOE. Kyte and Doolittle Hydrophobicity scores show that this variant may be less hydrophobic. Leu > Pro exchange may result is loss of hydrophobic interactions, thus destroying the contact between Helix4 and Helix1. Leu>Pro mutation of APOE may be associated with overproduction of amyloid protein instead of amyloid clearance. Magnetic resonance imaging of the patient reveals significant medial temporal lobe atrophy as well as a decreased Clinical Dementia Rating-Sum of Boxes scores over the years from the time of onset, indicating Leu>Pro mutation may affect the progression of Tau pathology along with amyloid burden. Impact of minor APOE variants are still unclear and this novel ε3/ε3 Leu>Pro mutation may manifest clinical symptom of early onset and progression of atypical Alzheimer's Disease.