👤 L Markó

Pro-opiomelanocortin (POMC) and the melanocortin-4 receptor (MC4R) play a pivotal role in the leptin-melanocortin pathway. Mutations in these genes lead to monogenic types of obesity due to severe hyperphagia. In addition to dietary-induced obesity, a cardiac phenotype without hypertrophy has been identified in MC4R knockout mice. We aimed to characterize cardiac morphology and function as well as tissue Na+ content in humans with mutations in POMC and MC4R genes. A cohort of 42 patients (5 patients with bi-allelic POMC mutations, 6 heterozygous MC4R mutation carriers, 19 obese controls without known monogenic cause, and 12 normal weight controls) underwent cardiac magnetic resonance (CMR) imaging and 23Na-MRI. Monogenic obese patients with POMC or MC4R mutation respectively had a significantly lower left ventricular mass/body surface area (BSA) than nonmonogenic obese patients. Left ventricular end-diastolic volume/BSA was significantly lower in POMC- and MC4R-deficient patients than in nonmonogenic obese patients. Subcutaneous fat and skin Na+ content was significantly higher in POMC- and MC4R-deficient patients than in nonmonogenic obese patients. In these compartments, the water content was significantly higher in patients with POMC and MC4R mutation than in control groups. Patients with POMC or MC4R mutations carriers had a lack of transition to hypertrophy, significantly lower cardiac muscle mass/BSA, and stored more Na+ within the subcutaneous fat tissue than nonmonogenic obese patients. The results point towards the role of the melanocortin pathway for cardiac function and tissue Na+ storage and the importance of including cardiologic assessments into the diagnostic work-up of these patients. Show less

In recent studies, the T-1131C variant of apolipoprotein A5 (APOA5) gene was found to confer a risk for metabolic syndrome (MS). Here we determined four haplotype-tagging polymorphisms (T-1131C, IVS3+G476A, T1259C, and C56G), and studied the distribution of the naturally occurring major haplotype profiles in MS. A total of 343 MS patients and 284 controls were genotyped using PCR-RFLP methods. Both in MS and control groups, we confirmed the already known association of -1131C, IVS3+473A and 1259C minor alleles with elevated triglyceride levels. The prevalence of the APOA5*2 haplotype (the combination of T-1131C, IVS3+G476A and T1259C SNPs) was 13.1% in MS patients, and 4.9% in controls (p<0.001); multiple logistic regression analysis revealed that this haplotype confers risk for the development of MS (OR=2.880; 95% CI: 1.567-5.292; p=0.001). We also observed a gender effect: in males a more prominent degree of susceptibility was found. Contrary to the APOA5*2 haplotype, the prevalence rate of APOA5*4 (determined by the T-1131C SNP alone) did not differ between MS patients and controls. We identified a novel haplotype, designated here as APOA5*5 (1259C allele alone); which appears to be protective against MS. Our results refined the role of SNP T-1131C in the development of MS. The susceptibility nature of this SNP is limited to the APOA5*2 haplotype, while in APOA5*4 haplotype it did not confer a risk for the disease. In addition, as our current data suggest, the novel APOA5*5 haplotype can confer protection against MS. Show less

Metabolic syndrome consists of multiple risk factors that are increasing the cardiovascular mortality. The T-1131C variant of the apolipoprotein A5 gene, associated with increased triglycerides, has been found to confer risk for cardiovascular diseases and metabolic syndrome. Because other naturally occurring variants of the gene also correlate with elevated triglycerides, the possible role of 2 common variants, the IVS3+G476A and T1259C, with metabolic syndrome was investigated. A total of 213 metabolic syndrome patients and 142 healthy controls were genotyped by polymerase chain reaction-restriction fragment length polymorphism. Serum triglycerides were increased in carriers compared with non-carriers in both groups (p<0.001); serum cholesterol levels were similar in all genotypes. The IVS3+476A allele frequency was increased in metabolic syndrome patients compared with controls (8.05 vs 2.47%; p<0.05), whereas the 1259C allele frequency did not differ between the groups. Multiple logistic regression analyses adjusted for age, gender, serum total cholesterol, acute myocardial infarction and stroke revealed that the IVS3+476A variant confers risk for development of metabolic syndrome (odds ratio =3.529, 95% confidence interval 1.308-9.029, p=0.009), but the 1259C allele had no such an effect. Carrying the IVS3+473A allele is associated with elevated triglycerides and confers risk for development of metabolic syndrome, a combination that represents increased risk for development of atherogenic vascular diseases. Show less

The -1131C is a naturally occurring variant of the apolipoprotein A5 (ApoA5) gene, which has been shown to associate with increased triglyceride levels. This variant has also been shown to confer risk for development of ischemic heart disease and stroke. The gene is in linkage disequilibrium with factors known to correlate with impaired glucose homeostasis. These observations prompted us to study the prevalence of the ApoA5 -1131C allele in patients with metabolic syndrome. A total of 201 metabolic syndrome patients and 210 controls were studied. In both groups the triglyceride levels of patients with -1131C allele were significantly increased compared to the subjects with -1131T allele (3.22+/-0.43 mmol/l vs. 2.24+/-0.12 mmol/l, p<0.01 in the metabolic syndrome patients; 2.10+/-0.19 mmol/l vs. 1.22+/-0.05 mmol/l, p<0.01 in the controls). In metabolic syndrome patients the prevalence of the ApoA5 -1131C variant was increased compared to the healthy controls (11% vs. 6.20%). Multiplex regression analysis model adjusted for age, gender, serum total cholesterol levels, acute myocardial infarction and stroke events revealed that the examined ApoA5 variant confers risk for the development of metabolic syndrome: the odds ratio at 95% confidence interval was 3.622 (1.200-10.936), p=0.02. Our findings strongly suggest that this variant is a risk factor for the development of hypertriglyceridemia and metabolic syndrome. Show less