Genetic Polymorphisms and Genetic Risk Scores Contribute to the Risk of Coronary Artery Disease (CAD) in a North Indian Population.

Coronary artery disease (CAD) is the leading cause of death in India. Many genetic polymorphisms play a role in regulating oxidative stress, blood pressure and lipid metabolism, contributing to the pathophysiology of CAD. This study examined the association between ten polymorphisms and CAD in the Jat Sikh population from Northern India, also considering polygenic risk scores. This study included 177 CAD cases and 175 healthy controls. The genetic information of GSTM1 (rs366631), GSTT1 (rs17856199), ACE (rs4646994), AGT M235T (rs699), AGT T174M (rs4762), AGTR1 A1166C (rs5186), APOA5 (rs3135506), APOC3 (rs5128), APOE (rs7412) and APOE (rs429358) and clinical information was collated. Statistical analyses were performed using SPSS version 27.0 and SNPstats. Significant independent associations were found for GST*M1, GST*T1, ACE, AGT M235T, AGT T174M, AGTR1 A1166C and APOA5 polymorphisms and CAD risk (all p < 0.05). The AGT CT haplotype was significantly associated with a higher CAD risk, even after controlling for covariates (adjusted OR = 3.93, 95% CI [2.39-6.48], p < 0.0001). The APOA5/C3 CC haplotype was also significantly associated with CAD (adjusted OR = 1.86, 95% CI [1.14-3.03], p < 0.05). A higher polygenic risk score was associated with increased CAD risk (adjusted OR = 1.98, 95% CI [1.68-2.34], p < 0.001). Seven polymorphisms were independently associated with an increase in the risk of CAD in this North Indian population. A considerable risk association of AGT, APOA5/C3 haplotypes and higher genetic risk scores is documented, which may have implications for clinical and public health applications.

Monogenic hypertriglyceridemia and recurrent pancreatitis in a homozygous carrier of a rare APOA5 mutation: a case report.

BACKGROUND: Homozygous mutations in the APOA5 gene constitute a rare cause of monogenic hypertriglyceridemia, or familial chylomicronemia syndrome (FCS). We searched PubMed and identified 16 cases of homozygous mutations in the APOA5 gene. Severe hypertriglyceridemia related to monogenic mutations in triglyceride-regulating genes can cause recurrent acute pancreatitis. Standard therapeutic approaches for managing this condition typically include dietary interventions, fibrates, and omega-3-fatty acids. A novel therapeutic approach, antisense oligonucleotide volanesorsen is approved for use in patients with FCS. CASE PRESENTATION: We report a case of a 25-years old Afghani male presenting with acute pancreatitis due to severe hypertriglyceridemia up to 29.8 mmol/L caused by homozygosity in APOA5 (c.427delC, p.Arg143Alafs*57). A low-fat diet enriched with medium-chain TG (MCT) oil and fibrate therapy did not prevent recurrent relapses, and volanesorsen was initiated. Volanesorsen resulted in almost normalized triglyceride levels. No further relapses of acute pancreatitis occurred. Patient reported an improve life quality due to alleviated chronic abdominal pain and headaches. CONCLUSIONS: Our case reports a rare yet potentially life-threatening condition-monogenic hypertriglyceridemia-induced acute pancreatitis. The implementation of the antisense drug volanesorsen resulted in improved triglyceride levels, alleviated symptoms, and enhanced the quality of life.

APOA5 deficiency causes hypertriglyceridemia by reducing amounts of lipoprotein lipase in capillaries.

Apolipoprotein AV (APOA5) deficiency causes hypertriglyceridemia in mice and humans. For years, the cause remained a mystery, but the mechanisms have now come into focus. Here, we review progress in defining APOA5's function in plasma triglyceride metabolism. Biochemical studies revealed that APOA5 binds to the angiopoietin-like protein 3/8 complex (ANGPTL3/8) and suppresses its ability to inhibit the activity of lipoprotein lipase (LPL). Thus, APOA5 deficiency is accompanied by increased ANGPTL3/8 activity and lower levels of LPL activity. APOA5 deficiency also reduces amounts of LPL in capillaries of oxidative tissues (e.g., heart, brown adipose tissue). Cell culture experiments revealed the likely explanation: ANGPTL3/8 detaches LPL from its binding sites on the surface of cells, and that effect is blocked by APOA5. Both the low intracapillary LPL levels and the high plasma triglyceride levels in Apoa5-/- mice are normalized by recombinant APOA5. Carboxyl-terminal sequences in APOA5 are crucial for its function; a mutant APOA5 lacking 40-carboxyl-terminal residues cannot bind to ANGPTL3/8 and lacks the ability to change intracapillary LPL levels or plasma triglyceride levels in Apoa5-/- mice. Also, an antibody against the last 26 amino acids of APOA5 reduces intracapillary LPL levels and increases plasma triglyceride levels in wild-type mice. An inhibitory ANGPTL3/8-specific antibody functions as an APOA5-mimetic reagent, increasing intracapillary LPL levels and lowering plasma triglyceride levels in both Apoa5-/- and wild-type mice. That antibody is a potentially attractive strategy for treating elevated plasma lipid levels in human patients.

Consumption of dietary fiber and APOA5 genetic variants in metabolic syndrome: baseline data from the Korean Medicine Daejeon Citizen Cohort Study.

BACKGROUND: Consumption of dietary fiber has been suggested as an important aspect of a healthy diet to reduce the risk of metabolic syndrome (MetS), including cardiovascular disease. The role of fiber intake in MetS might differ by individual genetic susceptibility. APOA5 encodes a regulator of plasma triglyceride levels, which impacts the related mechanisms of MetS. This study investigated the association between dietary fiber and the risk of MetS, assessing their associations according to APOA5 genetic variants. METHODS: A total of 1985 participants aged 30-55 years were included from a cross-sectional study based on the Korean Medicine Daejeon Citizen Cohort study at baseline (2017-2019). Dietary fiber intake was measured using a semiquantitative food frequency questionnaire. The APOA5 polymorphisms (rs2266788 A > G, rs662799 A > G, and rs651821 T > C) were genotyped using the Asia Precision Medicine Research Array. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: A higher consumption of dietary fiber was associated with a lower prevalence of MetS (P = 0.025). Among the components of MetS, an inverse association with dietary fiber was observed in increased waist circumference (OR, 95% CI = 0.60, 0.41-0.88, P for trend = 0.009) and elevated triglycerides (OR, 95% CI = 0.69, 0.50-0.96, P for trend = 0.012). Regarding the interaction with APOA5 genetic variants, a stronger association with dietary fiber intake was shown in G allele carriers of rs662799 than in A/A carriers (OR, 95% CI = 2.34, 1.59-3.44, P for interaction = 0.024) and in C allele carriers of rs651821 than in T/T carriers (OR, 95% CI = 2.35, 1.59-3.46, P for interaction = 0.027). CONCLUSIONS: The findings of this study suggest that the benefits of dietary fiber on the risk of MetS could be modified by genetic variants of the APOA5 gene, providing a more effective strategy for preventing MetS.

A unified model for regulating lipoprotein lipase activity.

The regulation of triglyceride (TG) tissue distribution, storage, and utilization, a fundamental process of energy homeostasis, critically depends on lipoprotein lipase (LPL). We review the intricate mechanisms by which LPL activity is regulated by angiopoietin-like proteins (ANGPTL3, 4, 8), apolipoproteins (APOA5, APOC3, APOC2), and the cAMP-responsive element-binding protein H (CREBH). ANGPTL8 functions as a molecular switch, through complex formation, activating ANGPTL3 while deactivating ANGPTL4 in their LPL inhibition. The ANGPTL3-4-8 model integrates the roles of the aforementioned proteins in TG partitioning between white adipose tissue (WAT) and oxidative tissues (heart and skeletal muscles) during the feed/fast cycle. This model offers a unified perspective on LPL regulation, providing insights into TG metabolism, metabolic diseases, and therapeutics.

Nomogram developed with APOA5 genetic variant rs662799 and clinical characteristics predicting risk of essential hypertension in a Chinese population.

Background: The apolipoprotein A5 (APOA5) gene has been identified as a key regulatory factor in triglyceride (TG) metabolism and plasma lipid levels. Genetic polymorphisms of APOA5 have been linked to an elevated risk of atherosclerosis, metabolic syndrome, stroke, and coronary artery disease. The rs662799 variant is a single nucleotide polymorphism (SNP) that occurs at a specific position within the APOA5 gene. However, the association between rs662799 polymorphism and essential hypertension (EHT) remains unclear. The study aimed to comprehensively examine the potential correlation between the rs662799 polymorphism and the susceptibility to EHT in a Chinese population using a systematic analysis. Methods: In a case study conducted at the First Affiliated Hospital of Xinjiang Medical University between Jan 2019 and Dec 2021, we examined a total of 700 cases of EHT along with 700 corresponding controls. The serum concentrations of various lipid parameters were measured by enzymatic method, while the genotyping of the SNP was performed using the improved multiplex ligation detection reaction (iMLDR) method. The independent risk factors of EHT were identified from multivariable logistic regression analysis. The nomogram prediction model that incorporated the APOA5 genetic variations and clinical variables was constructed. In addition, receiver operating characteristic (ROC) curve and Hosmer-Lemeshow test were conducted to determine the performance of the nomogram model. The optimal threshold was calculated based on Youden index. Results: Our study revealed a higher prevalence of the G allele of the rs662799 variant in individuals diagnosed with EHT compared to the control group. Logistic regression analysis indicated that with the adjustment of other confounders, the observed difference between the two groups remained statistically significant [odds ratio (OR) =1.519; 95% confidence interval (CI): 1.203-1.917; P<0.001]. Based on 8 independent risk factors including APOA5 rs662799 G allele, age, body mass index (BMI), smoking, diabetes, education, low-density lipoprotein cholesterol (LDL-C), and TG, we constructed a novel risk evaluation nomogram of EHT. The area under the ROC curve of the nomogram was 0.722 (95% CI: 0.693-0.752; P<0.001) and 0.747 (95% CI: 0.690-0.804; P<0.001) for the training and validation set, respectively. Furthermore, the Hosmer-Lemeshow test indicated excellent calibration performance, yielding P values of 0.969 for the training set and 0.761 for the validation set. Conclusions: In our study, the rs662799 variant of the APOA5 gene was significantly associated with susceptibility to EHT. A nomogram for the early prediction of EHT in in the Chinese population was successfully constructed and validated. The nomogram can provide a visual assessment of the risk of EHT for clinical consultation.

Overexpression of salusin­α upregulates AdipoR2 and activates the PPARα/ApoA5/SREBP­1c pathway to inhibit lipid synthesis in HepG2 cells.

Salusin­α and adiponectin, are vasoactive peptides with numerous similar biological effects related to lipid metabolism. Adiponectin has been shown to reduce fatty acid oxidation and to inhibit lipid synthesis of liver cells through its receptor, adiponectin receptor 2 (AdipoR2), but whether salusin­α is able to interact with AdipoR2, was not previously reported. To investigate this, in vitro experiments were carried out. The overexpression and interference recombinant plasmids were constructed with salusin­α. The lentiviral expression systems of salusin­α overexpression and interference were respectively synthesized in 293T cells, and 293T cells were infected with the lentivirus. Finally, the association between salusin­α and AdipoR2 was analyzed by semi­quantitative PCR. Subsequently, HepG2 cells were also infected with these viruses. The expression levels of AdipoR2, peroxisome proliferator­activated receptor­α (PPARα), apolipoprotein A5 (ApoA5) and sterol regulatory element­binding transcription factor 1 (SREBP­1c) were detected by western blotting, and AdipoR2 inhibitor (thapsigargin) and agonist [4­phenyl butyric acid (PBA)] were used to observe the resultant changes in the aforementioned molecules. The results obtained revealed that the overexpression of salusin­α increased the level of AdipoR2 in 293T and HepG2 cells, led to an upregulation of the levels of PPARα and ApoA5, and inhibited the expression of SREBP­1c, whereas the salusin­α interference lentivirus exerted the opposite effects. Notably, thapsigargin inhibited the expression of AdipoR2, PPARα and ApoA5 in HepG2 cells of pHAGE­Salusin­α group, and caused an increase in the level of SREBP­1c, whereas the opposite effects were observed in pLKO.1­shSalusin­α#1 group upon treatment with PBA. Taken together, these data demonstrated that overexpression of salusin­α upregulated AdipoR2, which in turn activated the PPARα/ApoA5/SREBP­1c signaling pathway to inhibit lipid synthesis in HepG2 cells, thereby providing theoretical data on which to base the clinical application of salusin­α as a novel peptide for molecular intervention in fatty liver disease.

Comparison of the structure-function properties of wild-type human apoA-V and a C-terminal truncation associated with elevated plasma triglycerides.

Background: Plasma triglycerides (TGs) are causally associated with coronary artery disease and acute pancreatitis. Apolipoprotein A-V (apoA-V, gene APOA5) is a liver-secreted protein that is carried on triglyceride-rich lipoproteins and promotes the enzymatic activity of lipoprotein lipase (LPL), thereby reducing TG levels. Little is known about apoA-V structure-function; naturally occurring human APOA5 variants can provide novel insights. Methods: We used hydrogen-deuterium exchange mass spectrometry to determine the secondary structure of human apoA-V in lipid-free and lipid-associated conditions and identified a C-terminal hydrophobic face. Then, we used genomic data in the Penn Medicine Biobank to identify a rare variant, Q252X, predicted to specifically eliminate this region. We interrogated the function of apoA-V Q252X using recombinant protein in vitro and in vivo in apoa5 knockout mice. Results: Human apoA-V Q252X carriers exhibited elevated plasma TG levels consistent with loss of function. Apoa5 knockout mice injected with AAV vectors expressing wildtype and variant APOA5-AAV recapitulated this phenotype. Part of the loss of function is due to reduced mRNA expression. Functionally, recombinant apoA-V Q252X was more readily soluble in aqueous solutions and more exchangeable with lipoproteins than WT apoA-V. Despite lacking the C-terminal hydrophobic region (a putative lipid binding domain) this protein also decreased plasma TG in vivo. Conclusions: Deletion of apoA-V's C-terminus leads to reduced apoA-V bioavailability in vivo and higher TG levels. However, the C-terminus is not required for lipoprotein binding or enhancement of intravascular lipolytic activity. WT apoA-V is highly prone to aggregation, and this property is markedly reduced in recombinant apoA-V lacking the C-terminus.

Comprehensive in-silico analysis of deleterious SNPs in APOC2 and APOA5 and their differential expression in cancer and cardiovascular diseases conditions.

Genetic variations in APOC2 and APOA5 genes involve activating lipoprotein lipase (LPL), responsible for the hydrolysis of triglycerides (TG) in blood and whose impaired functions affect the TG metabolism and are associated with metabolic diseases. In this study, we investigate the biological significance of genetic variations at the DNA sequence and structural level using various computational tools. Subsequently, 8 (APOC2) and 17 (APOA5) non-synonymous SNPs (nsSNPs) were identified as high-confidence deleterious SNPs based on the effects of the mutations on protein conservation, stability, and solvent accessibility. Furthermore, based on our docking results, the interaction of native and mutant forms of the corresponding proteins with LPL depicts differences in root mean square deviation (RMSD), and binding affinities suggest that these mutations may affect their function. Furthermore, in vivo, and in vitro studies have shown that differential expression of these genes in disease conditions due to the influence of nsSNPs abundance may be associated with promoting the development of cancer and cardiovascular diseases. Preliminary screening using computational methods can be a helpful start in understanding the effects of mutations in APOC2 and APOA5 on lipid metabolism; however, further wet-lab experiments would further strengthen the conclusions drawn from the computational study.

A Clinical Case of a Homozygous Deletion in the APOA5 Gene with Severe Hypertriglyceridemia.

Background: Hypertriglyceridemia (HTG) is one of the most common forms of lipid metabolism disorders. The leading clinical manifestations are pancreatitis, atherosclerotic vascular lesions, and the formation of eruptive xanthomas. The most severe type of HTG is primary (or hereditary) hypertriglyceridemia, linked to pathogenic genetic variants in LPL, APOC2, LMF1, and APOA5 genes. Case: We present a clinical case of severe primary hypertriglyceridemia (TG level > 55 mmol/L in a 4-year-old boy) in a consanguineous family. The disease developed due to a previously undescribed homozygous deletion in the APOA5 gene (NM_052968: c.579_592delATACGCCGAGAGCC p.Tyr194Gly*68). We also evaluate the clinical significance of a genetic variant in the LPL gene (NM_000237.2: c.106G>A (rs1801177) p.Asp36Asn), which was previously described as a polymorphism. In one family, we also present a different clinical significance even in heterozygous carriers: from hypertriglyceridemia to normotriglyceridemia. We provide evidence that this heterogeneity has developed due to polymorphism in the LPL gene, which plays the role of an additional trigger. Conclusions: The homozygous deletion of the APOA5 gene is responsible for the severe hypertriglyceridemia, and another SNP in the LPL gene worsens the course of the disease.

Apolipoprotein A5, a unique modulator of fasting and postprandial triglycerides.

The discovery of apolipoprotein A5 (APOA5) in 2001 has raised a number of intriguing questions about its role in lipid transport and triglyceride (TG) homeostasis. Genome-wide association studies have consistently identified APOA5 as a regulator of plasma TG levels, which is further supported by studies in transgenic and knockout mouse models. The present review describes recent concepts pertaining to the roles of APOA5 in TG metabolism as related to the vascular compartment, liver, adipose tissue and the gut. Recent evidence indicates that APOA5 may also affect postprandial TG metabolism through influencing chylomicron formation and transport by the intestine into the intestinal lymph. While substantial evidence supports the notion that APOA5 plays both extracellular and intracellular roles in TG homeostasis, mysteries remain on how this low-abundance, liver-derived protein may modulate TG homeostasis, including via the gut. Given the strong correlation between elevated plasma TG and cardiometabolic diseases, there is great scientific and public interest in understanding the intriguing mysteries presented by APOA5.

Association of the APOA-5 Genetic Variant rs662799 with Metabolic Changes after an Intervention for 9 Months with a Low-Calorie Diet with a Mediterranean Profile.

In cross-sectional studies, the genetic variant rs662799 of the APOA5 gene is associated with high serum triglyceride concentrations, and in some studies, the effect of short-term dietary interventions has been evaluated. The aim of the present investigation was to evaluate the role of this genetic variant in metabolic changes after the consumption of a low-calorie diet with a Mediterranean pattern for 9 months. A population of 269 Caucasian obese patients was recruited. Adiposity and biochemical parameters were measured at the beginning (basal level) and after 3 and 9 months of the dietary intervention. The rs662799 genotype was assessed with a dominant analysis (TT vs. CT + CC). The APOA5 variant distribution was: 88.1% (n = 237) (TT), 11.5% (n = 31) (TC) and 0.4% (n = 1) (CC). There were significant differences only in triglyceride levels at all times of the study between the genotype groups. After 3 and 9 months of dietary intervention, the following parameters improved in both genotype groups: adiposity parameters, systolic pressure, total cholesterol, LDL cholesterol, leptin, adiponectin and the leptin/adiponectin ratio. The intervention significantly decreased insulin levels, HOMA-IR and triglyceride levels in non-C allele carriers (Delta 9 months TT vs. TC + CC). i.e., insulin levels (delta: -3.8 + 0.3 UI/L vs. -1.2 + 0.2 UI/L; p = 0.02), HOMA-IR levels (delta: -1.2 + 0.2 units vs. -0.3 + 0.1 units; p = 0.02), triglyceride levels (delta: -19.3 + 4.2 mg/dL vs. -4.2 + 3.0 mg/dL; p = 0.02). In conclusion, non-C allele carriers of rs662799 of the APOA5 gene showed a decrease of triglyceride, insulin and HOMA-IR levels after consuming a low-calorie diet with a Mediterranean pattern; we did not observe this effect in C allele carriers, despite a significant weight loss.

Changes in adiposity modulate the APOA5 genetic effect on blood lipids: A longitudinal cohort study.

BACKGROUND AND AIMS: The Apolipoprotein A5 (APOA5) rs662799 was significantly associated with blood lipid level at genome-wide significance level. Whether dynamic changes of adiposity influence the effect of lipid loci on long-term blood lipid profile remains unclear. We assessed interactions of 5-year body mass index (BMI) change and rs662799 genotypes with risk of incident dyslipidemia and longitudinal changes in serum lipids in a prospective cohort. METHODS: We included 4329 non-dyslipidemia participants aged ≥ 40 years at baseline from a well-defined community-based cohort and followed up for an average of 5 years. BMI and blood lipids were measured at baseline and follow-up. RESULTS: The association of each rs662799 A-allele with risk of incident dyslipidemia was stronger along with the increase in BMI change level, with the odds ratios (OR) increasing from 1.03 in the lowest tertile of BMI change (< 0.02 kg/m2) to 1.17 in the second (0.02-1.29), and 1.46 in the highest tertile (> 1.29) (pfor interaction< 0.001). Associations of each 1-unit of BMI (kg/m2) increase with incident dyslipidemia were more prominent in the AA carriers (OR = 1.50, 95%CI [1.26-1.80], p < 0.001), while much weaker in the GA (OR = 1.10) or GG carriers (OR = 1.09) (pfor interaction = 0.002). Similar results were found for the risk of incident higher triglycerides (TG) and lower high-density lipoprotein cholesterol (HDL-c), or the longitudinal changes in log10-TG (all pfor interaction ≤ 0.02). CONCLUSIONS: BMI changes significantly modulate rs662799 genetic contribution to dyslipidemia and long-term lipid profile, which provide new evidence for personalized clinical management of lipids according to individual genetic background.

Interactions between red and processed meat consumption and APOA5 gene variants associated with the incidence of metabolic syndrome in Korean adults.

BACKGROUND: Metabolic syndrome (MetS) is characterized by the coexistence of disorders such as diabetes, hypertension, hyperlipidemia, and obesity and is affected by genetic factors. Previous genome-wide association studies (GWAS) suggested that APOA5 gene variants were significantly associated with MetS and its components. Dietary factors such as red and processed meat consumption can cause chronic diseases, including hypertension, diabetes, and vascular depression. The aim of this study was to investigate the modulation of the incidence of MetS by the interaction between APOA5 rs662799 polymorphism and red and processed meat consumption. METHODS: In this prospective cohort study, 3266 participants were collected from the Korea Association REsource (KARE) cohort of the Korean Genome and Epidemiology Study (KoGES) from 2001 to 2016. APOA5 rs662799 polymorphism was extracted by GWAS using the Korean Chip. Red and processed meat consumption data were assessed using a semi-quantitative food frequency questionnaire. RESULTS: The incidence of MetS in carriers of the minor G allele of rs662799 (AG + GG) and the third tertile of red and processed meat consumption (serving/day) was higher than those with the major allele of rs662799 (AA) and the first tertile of red and processed meat consumption (HR 1.70, 95% CI 1.30-2.22, p interaction = 0.002). CONCLUSIONS: An association between the presence of the minor alleles of rs662799 and high red and processed meat consumption and the incidence of MetS was observed in Korean adults.

Epigenetic changes induced in mice liver by methionine-supplemented and methionine-deficient diets.

A diet deficient in donors of methyl group, such as methionine, affects DNA methylation and hepatic lipid metabolism. Methionine also affects other epigenetic mechanisms, such as microRNAs. We investigated the effects of methionine-supplemented or methionine-deficient diets on the expression of chromatin-modifying genes, global DNA methylation, the expression and methylation of genes related to lipid metabolism, and the expression of microRNAs in mouse liver. Female Swiss albino mice were fed a control diet (0.3% methionine), a methionine-supplemented diet (2% methionine), and a methionine-deficient diet (0% methionine) for 10 weeks. The genes most affected by the methionine-supplemented diet were associated with histone and DNA methyltransferases activity, while the methionine-deficient diet mostly altered the expression of histone methyltransferases genes. Both diets altered the global DNA methylation and the expression and gene-specific methylation of the lipid metabolism gene Apoa5. Both diets altered the expression of several liver homeostasis-related microRNAs, including miR-190b-5p, miR-130b-3p, miR-376c-3p, miR-411-5p, miR-29c-3p, miR-295-3p, and miR-467d-5p, with the methionine-deficient diet causing a more substantial effect. The effects of improper amounts of methionine in the diet on liver pathologies may involve a cooperative action of chromatin-modifying genes, which results in an aberrant pattern of global and gene-specific methylation, and microRNAs responsible for liver homeostasis.

Biochemical, Clinical, and Genetic Characteristics of Mexican Patients with Primary Hypertriglyceridemia, Including the First Case of Hyperchylomicronemia Syndrome Due to GPIHBP1 Deficiency.

Primary hypertriglyceridemia (PHTG) is characterized by a high concentration of triglycerides (TG); it is divided between familial hyperchylomicronemia syndrome and multifactorial chylomicronemia syndrome. In Mexico, hypertriglyceridemia constitutes a health problem in which the genetic bases have been scarcely explored; therefore, our objective was to describe biochemical-clinical characteristics and variants in the APOA5, GPIHBP1, LMF1, and LPL genes in patients with primary hypertriglyceridemia. Thirty DNA fragments were analyzed using PCR and Sanger sequencing in 58 unrelated patients. The patients' main clinical-biochemical features were hypoalphalipoproteinemia (77.6%), pancreatitis (18.1%), and a TG median value of 773.9 mg/dL. A total of 74 variants were found (10 in APOA5, 16 in GPIHBP1, 34 in LMF1, and 14 in LPL), of which 15 could be involved in the development of PHTG: 3 common variants with significative odds and 12 heterozygous rare pathogenic variants distributed in 12 patients. We report on the first Mexican patient with hyperchylomicronemia syndrome due to GPIHBP1 deficiency caused by three variants: p.R145*, p.A154_G155insK, and p.A154Rfs*152. Moreover, eleven patients were heterozygous for the rare variants described as causing PHTG and also presented common variants of risk, which could partially explain their phenotype. In terms of findings, two novel genetic variants, c.-40_-22del LMF1 and p.G242Dfs*10 LPL, were identified.

APOA5 Variant rs662799, Role in Cardiovascular Traits and Serum Adipokine Levels in Caucasian Obese Subjects.

BACKGROUND AND AIMS: This ApoA5-1131C allele of rs662799 variant is related with a higher serum triglyceride levels, and it contributes to increase risk of cardiovascular disease. The aim of the present investigation was to evaluate single nucleotide polymorphism rs662799 in APOA5 gene and its associations with cardiovascular risk factors, MS, and serum adipokine levels. METHODS: The study involved a population of 1,002 Caucasian obese subjects. Measurements of body weight, waist circumference, fat mass, arterial blood pressure, blood glucose, C-reactive protein, insulin levels, insulin resistance (HOMA-IR), lipid profile, and adipokines levels were recorded. Genotype of ApoA5 gene polymorphism (rs662799) and prevalence of metabolic syndrome (MS) were evaluated. RESULTS: The distribution of the rs662799 polymorphism in this adult population (n = 1,002) was 88.3% (n = 885) (TT), 11.4% (n = 114) (TC), and 0.3% (n = 3) (CC). No significant differences were found between the 2 genotypes in the anthropometric data, MS, or blood pressure. Triglyceride levels were higher in C-allele carriers (delta total group: 19.7 ± 2.1 mg/dL: p = 0.02) than non C-allele carriers. HDL-cholesterol levels were lower in C-allele carriers (delta total group: -6.7 ± 1.1 mg/dL: p = 0.02) than non C-allele carriers. Adiponectin levels were lower in C-allele carriers (delta total group: -11.6 ± 1.0 mg/dL: p = 0.02) too. In C-allele carriers, logistic regression analysis showed an increased risk of hypertriglyceridemia (odds ratio [OR] = 2.1, 95% confidence interval [CI] = 1.2-3.4, p = 0.001) and percentage of low-HDL-C (OR = 2.2, 95% CI = 1.3-3.7, p = 0.002) after adjusting by body mass index and age. CONCLUSIONS: C-allele carriers of rs662799 of APOA5 gene showed high rates of low levels of HDL and hypertriglyceridemia, with differences in triglyceride, HDL cholesterol, and adiponectin levels in Caucasian obese subjects.

Digenic Inheritance and Gene-Environment Interaction in a Patient With Hypertriglyceridemia and Acute Pancreatitis.

The etiology of hypertriglyceridemia (HTG) and acute pancreatitis (AP) is complex. Herein, we dissected the underlying etiology in a patient with HTG and AP. The patient had a 20-year history of heavy alcohol consumption and an 8-year history of mild HTG. He was hospitalized for alcohol-triggered AP, with a plasma triglyceride (TG) level up to 21.4 mmol/L. A temporary rise in post-heparin LPL concentration (1.5-2.5 times of controls) was noted during the early days of AP whilst LPL activity was consistently low (50∼70% of controls). His TG level rapidly decreased to normal in response to treatment, and remained normal to borderline high during a ∼3-year follow-up period during which he had abstained completely from alcohol. Sequencing of the five primary HTG genes (i.e., LPL, APOC2, APOA5, GPIHBP1 and LMF1) identified two heterozygous variants. One was the common APOA5 c.553G > T (p.Gly185Cys) variant, which has been previously associated with altered TG levels as well as HTG-induced acute pancreatitis (HTG-AP). The other was a rare variant in the LPL gene, c.756T > G (p.Ile252Met), which was predicted to be likely pathogenic and found experimentally to cause a 40% loss of LPL activity without affecting either protein synthesis or secretion. We provide evidence that both a gene-gene interaction (between the common APOA5 variant and the rare LPL variant) and a gene-environment interaction (between alcohol and digenic inheritance) might have contributed to the development of mild HTG and alcohol-triggered AP in the patient, thereby improving our understanding of the complex etiology of HTG and HTG-AP.

Diseño y validación de un ensayo de minisecuenciación múltiple para detectar polimorfismos asociados con Síndrome Metabólico / Design and validation of a multiple minisequencing assay to detect polymorphisms associated with Metabolic Syndrome

Resumen Introducción: Es importante identificar los polimorfismos de interés clínico en patologías complejas como el Síndrome Metabólico. Por esto, las metodologías para su evaluación deben estar diseñadas y validadas correctamente, esto permite optimizar recursos y tiempo en la genotipificación y detección correcta de los alelos presentes en los individuos. Objetivo: Diseñar y validar una PCR múltiple, seguida de detección por minisecuenciación, para la genotipificación de ocho polimorfismos de nucleótido simple ubicados en el gen del Receptor Beta 3-Adrenérgico (rs4994 y rs4998), gen de la Apolipoproteina A5 (rs3135506 y rs2075291), gen de la Adiponectina (rs1501299 y rs2241766) y gen del Receptor Activador de la Proliferación de los Peroxisomas tipo gamma (rs1801282 y rs1800571), asociados con el síndrome metabólico. Materiales y métodos: Se diseñaron 24 cebadores para la amplificación y detección de ocho polimorfismos de nucleótido sencillo ubicados en cuatro genes candidatos a estar asociados con el síndrome metabólico, usando el software Primer3®. Dieciséis fueron diseñados para amplificar los polimorfismos y ocho para detectarlos por minisecuenciación. Las estructuras secundarias entre los cebadores se verificaron con el software Autodimer. Los polimorfismos se amplificaron simultáneamente y los fragmentos amplificados se acoplaron a las sondas diseñadas para detectar por minisecuenciación el alelo presente, por medio de bases marcadas con fluorocromos. Finalmente, los alelos fueron detectados por electroforesis capilar en un analizador genético ABI 310 y se interpretaron con el software GeneMapper®. La validación del multiplex se realizó genotipando 20 muestras de individuos, cada uno de ellos autorizó este procedimiento por medio del consentimiento informado. Resultados: Se obtuvieron los perfiles genéticos de los 20 controles genotipados, a partir de la amplificación múltiple, seguida de minisecuenciación, diseñada y validada para detectar los ocho polimorfismos. Conclusión: Se diseñó y validó un ensayo para la detección simultánea de los polimorfismos, ubicados en cuatro genes asociados con el Síndrome metabólico. Los cuales pueden ser empleados como referencia para futuros estudios poblacionales.

Abstract Introduction: It is important to identify the polymorphisms of clinical interest in complex pathologies such as Metabolic Syndrome. Therefore, the methodologies for its evaluation must be designed and validated correctly, this permits optimization of resources and time in genotyping and correct detection of the alleles present in individuals. Objective: To design and validate a multiplex PCR, followed by detection by minisequencing, for the genotyping of eight single nucleotide polymorphisms located in the Beta 3-Adrenergic Receptor gene (rs4994 and rs4998), Apolipoprotein A5 gene (rs3135506 and rs2075291), Adiponectin gene (rs1501299 and rs2241766) and gamma-type Peroxisome Proliferation Activating Receptor gene (rs1801282 and rs1800571), associated with metabolic syndrome. Materials and methods: Twenty-four primers were designed for the amplification and detection of eight single nucleotide polymorphisms located in four candidate genes to be associated with the metabolic syndrome, using the Primer3® software. Sixteen were designed to amplify the polymorphisms and eight to detect them by minisequencing. The secondary structures between the primers were verified with Autodimer software. The polymorphisms were simultaneously amplified, and the amplified fragments were coupled to probes designed to minisequence the present allele using fluorochrome-labeled bases. Finally, the alleles were detected by capillary electrophoresis using an ABI 310 genetic analyzer and analyzed with the GeneMapper® software. The validation of the multiplex was performed by genotyping 20 individual samples, each of them authorized this procedure through informed consent. Results: The genetic profiles of the 20 genotyped controls were obtained, from multiple amplification, followed by minisequencing, designed and validated to detect the eight polymorphisms. Conclusion: An essay was designed and validated for the simultaneous detection of polymorphisms, located in four genes associated with metabolic syndrome, and can used as a reference for future population studies.

Implication between Genetic Variants from APOA5 and ZPR1 and NAFLD Severity in Patients with Hypertriglyceridemia.

BACKGROUND: Lipid metabolism disorders, especially hypertriglyceridemia (HTG), are risk factors for non-alcoholic fatty liver disease (NAFLD). However, the association between genetic factors related to HTG and the risk of NAFLD has been scarcely studied. METHODS: A total of 185 subjects with moderate HTG were prospectively included. We investigated the association between genetic factors' (five allelic variants with polygenic hypertriglyceridemia) clinical and biochemical biomarkers with NAFLD severity. The five allelic variants' related clinical and biochemical data of HTG were studied in all the subjects. NAFLD was assessed by abdominal ultrasound and patients were divided into two groups, one with no or mild NAFLD and another with moderate/severe NAFLD. RESULTS: Patients with moderate/severe NAFLD had higher weight and waist values and a higher prevalence of insulin resistance than patients with no or mild NAFLD. Moderate/severe NAFLD was independently associated with APOA5 rs3134406 and ZPR1 rs964184 variants, and also showed a significant inverse relationship with lipoprotein(a) [Lp(a)] concentrations. CONCLUSIONS: APOA5 rs3135506 and ZPR1 rs964184 variants and lipoprotein(a) are associated with moderate/severe NAFLD. This association was independent of body weight, insulin resistance, and other factors related to NAFLD.