Vanessa Suñé Mattevi

Association analysis of genes involved in the leptin-signaling pathway with obesity in Brazil

OBJECTIVE: To investigate associations of polymorphisms in the LEP, LEPR and NPY genes with obesity-related traits in a Brazilian population of European descent.METHODS: A total of 183 women and 153 men (mean body mass index (BMI), 26.1±4.8 kg/m2) were genotyped using the PCR-RFLP procedure for the LEP A19G, LEPR Gln223Arg, LEPR PRO1019pro and NPY Leu7Pro polymorphisms. Frequencies were compared among normal-weight and overweight plus obese groups with chi-square tests, mean BMI and waist circumference were compared among genotypes by t-tests and analysis of variance.RESULTS: The genotype and allele frequencies of the LEPR Gln223Arg polymorphism were significantly different between normal-weight and overweight plus obese groups (P=0.013 and 0.009, respectively). Although there was no difference in the mean adjusted BMI among the three LEPRGln223Arg genotypes, a trend was observed for Arg/Arg individuals to have a higher mean BMI compared to Gln/Gln homozygotes, with heterozygote individuals presenting intermediate mean BMI between the two homozygote groups (ANOVA, P=0.063). However, in non-smokers, the LEPR Gln223Arg polymorphism showed a highly significant effect over BMI (P=0.009). When the analysis was restricted to premenopausal women, a highly significant effect of NPY was observed. Women bearing the Pro variant presented a lower BMI than wild-type homozygotes (P=0.001).CONCLUSION: Our findings suggest that genetic variability in the leptin receptor and neuropeptide Y genes is implicated in body weight regulation, the LEPR Gln223Arg variant being associated with a BMI increase in this Caucasian population, especially in non-smokers, while the NPY Leu7Pro polymorphism was associated with BMI reduction in premenopausal women.

Cannabinoid type-1 receptor gene polymorphisms are associated with central obesity in a Southern Brazilian population

The CB1 cannabinoid receptor and its endogenous ligands, the endocannabinoids, are involved in energy balance control, stimulating appetite and increasing body weight in wasting syndromes. Different studies have investigated the relationship between polymorphisms of the cannabinoid receptor 1 (CNR1) gene and obesity with conflicting results. In the present study, we investigated the 1359G/A (rs1049353), 3813A/G (rs12720071) and 4895A/G (rs806368) polymorphisms in the CNR1 gene in a Brazilian population of European descent. To verify the association between these variants and obesity-related traits in this population, 756 individuals were genotyped by PCR-RFLP methods. The 4895G allele was associated with waist to hip ratio (WHR) (P = 0.014; P = 0.042 after Bonferroni correction). An additive effect with the GAA haplotype was associated with WHR (P = 0.028), although this statistical significance disappeared after Bonferroni correction (P = 0.084). No significant association was observed between the genotypes of the 1359G/A and 3813A/G polymorphisms and any of the quantitative variables investigated. Our findings suggest that CNR1 gene polymorphism is associated with central obesity in this Brazilian population of European ancestry.

Multilocus Analyses of Seven Candidate Genes Suggest Interacting Pathways for Obesity‐Related Traits in Brazilian Populations

We investigated whether variants in major candidate genes for food intake and body weight regulation contribute to obesity‐related traits under a multilocus perspective. We studied 375 Brazilian subjects from partially isolated African‐derived populations (quilombos). Seven variants displaying conflicting results in previous reports and supposedly implicated in the susceptibility of obesity‐related phenotypes were investigated: β2‐adrenergic receptor (ADRB2) (Arg16Gly), insulin induced gene 2 (INSIG2) (rs7566605), leptin (LEP) (A19G), LEP receptor (LEPR) (Gln223Arg), perilipin (PLIN) (6209T > C), peroxisome proliferator‐activated receptor‐γ (PPARG) (Pro12Ala), and resistin (RETN) (−420C > G). Regression models as well as generalized multifactor dimensionality reduction (GMDR) were employed to test the contribution of individual effects and higher‐order interactions to BMI and waist‐hip ratio (WHR) variation and risk of overweight/obesity. The best multilocus association signal identified in the quilombos was further examined in an independent sample of 334 Brazilian subjects of European ancestry. In quilombos, only the PPARG polymorphism displayed significant individual effects (WHR variation, P = 0.028). No association was observed either with the risk of overweight/obesity (BMI ≥ 25 kg/m2), risk of obesity alone (BMI ≥ 30 kg/m2) or BMI variation. However, GMDR analyses revealed an interaction between the LEPR and ADRB2 polymorphisms (P = 0.009) as well as a third‐order effect involving the latter two variants plus INSIG2 (P = 0.034) with overweight/obesity. Assessment of the LEPR‐ADRB2 interaction in the second sample indicated a marginally significant association (P = 0.0724), which was further verified to be limited to men (P = 0.0118). Together, our findings suggest evidence for a two‐locus interaction between the LEPR Gln223Arg and ADRB2 Arg16Gly variants in the risk of overweight/obesity, and highlight further the importance of multilocus effects in the genetic component of obesity.

Genetic polymorphisms in estrogen receptors and sexual dimorphism in fat redistribution in HIV-infected patients on HAART.

Objective:To investigate genetic single nucleotide polymorphisms (SNPs) in estrogen receptor-&agr; (ER&agr;) (ESR1, rs2234693, rs1801132, rs7757956 and rs2813544) and ER&bgr; (ESR2, rs3020450, rs7154455 and rs4986938) genes and relate them to the adverse effects lipodystrophy, dyslipidemia and metabolic syndrome as well as to differences in their prevalence between sexes in HIV-infected individuals on HAART. Design:Cross-sectional study. Methods:Blood samples and anthropometric measurements were collected from 614 patients at reference services in the cities of Porto Alegre, Pelotas and Rio Grande in Brazil. The SNPs were genotyped by real-time PCR. Results:The lipodystrophy subtype frequencies in patients of different sexes showed statistically significant differences; the atrophic pattern was more prevalent in men, and the hypertrophic pattern was more prevalent in women. Furthermore, metabolic syndrome prevalence was higher in women than in men. The ESR1 rs2813544 G-allele was associated with higher measurements of several anthropometric variables in women: BMI, total subcutaneous fat and subcutaneous fat of limbs. Additionally, patients who were AA homozygous for ESR2 rs3020450 presented an increased risk for developing lipoatrophy (prevalence ratio 1.37, 95% confidence interval 1.09–1.73, P = 0.007). Conclusion:Significant differences in lipodystrophy and metabolic syndrome prevalence were detected between sexes. Moreover, the ESR1 gene (rs2813544) presented significant sex-specific associations with anthropometric variables, and the ESR2 gene (rs3020450) was associated with an increased risk of developing lipoatrophy. Our results suggest that these genes are in part responsible for the sexual dimorphism in fat tissue redistribution and patterns of lipodystrophy.

The role of mannose-binding lectin gene polymorphisms in susceptibility to HIV-1 infection in Southern Brazilian patients.

Objective:This study investigates the role of mannose-binding lectin (MBL) in the susceptibility to HIV-1 infection analyzing polymorphisms located at the MBL2 promoter and exon 1 regions. Materials and methods:The prevalence of MBL2 variant alleles was investigated in 410 HIV-1-infected patients from the South Brazilian HIV cohort and in 345 unexposed uninfected healthy individuals. The promoter variants were genotyped using polymerase chain reaction with sequence-specific primers (PCR-SSP) and exon 1 variants were analyzed by real-time PCR using a melting temperature assay and were confirmed by PCR-restriction fragment length polymorphism (RFLP). MBL2 genotypic and allelic frequencies were compared between HIV-1-infected patients and controls using the chi-squared tests. Results:The analyses were performed subdividing the individuals according to their ethnic origin. Among Euro-derived individuals a higher frequency of the LX/LX genotype was observed in patients when compared to controls (P < 0.001). The haplotypic analysis also showed a higher frequency of the haplotypes associated with lower MBL levels among HIV-1-infected patients (P = 0.0001). Among Afro-derived individuals the frequencies of LY/LY and HY/HY genotypes were higher in patients when compared to controls (P = 0.009 and P = 0.02). Conclusions:An increased frequency of MBL2 genotypes associated with low MBL levels was observed in Euro-derived patients, suggesting a potential role for MBL in the susceptibility to HIV-1 infection in Euro-derived individuals.

SNPs in the APM1 gene promoter are associated with adiponectin levels in HIV-infected individuals receiving HAART.

Objective: This study aimed to investigate the association between 4 polymorphisms in the leptin, leptin receptor, and adiponectin (APM1) genes and the occurrence of lipodystrophy and dyslipidemia in HIV-infected patients receiving highly active antiretroviral therapy (HAART). Materials and Methods: Genotypes of 410 HIV-infected patients on HAART were investigated. Anthropometric (weight, height, waist circumference and skinfolds thickness) and biochemical (blood lipids, glucose, leptin, and adiponectin levels) parameters were evaluated. Genotype frequencies were compared between patients with or without lipodystrophy. Mean biochemical and anthropometric parameters were compared between the different genotypes. Results: Lipodystrophy prevalence was 53.4%. Genotype frequencies were not different between patients with or without lipodystrophy. Carriers of the A allele for the APM1-11391 G>A and of the C allele for APM1-11377 C>G presented higher adiponectin levels compared to other genotypes, and carriers of the -11391A-11377C haplotype when compared with carriers of other haplotypes. Conclusions: SNPs in APM1 gene are associated with adiponectin levels in HIV-infected patients receiving HAART and may thus affect the occurrence of metabolic alterations in these patients. No influence of the leptin and leptin receptor gene polymorphisms on the occurrence of lipodystrophy and dyslipidemia was observed.

Lopinavir/ritonavir monotherapy as maintenance treatment in HIV-infected individuals with virological suppression: results from a pilot study in Brazil

The aim of the study was to evaluate the possibility of using lopinavir/ritonavir (LPV/RTV) alone as maintenance therapy in HIV‐infected individuals with virological suppression.

Polymorphisms in LEPR, PPARG and APM1 genes: associations with energy intake and metabolic traits in young children.

OBJECTIVE To assess the association of single nucleotide polymorphisms (SNPs) in five genes - leptin, leptin receptor (LEPR), adiponectin (APM1), peroxisome proliferator-activated receptor gamma (PPARG) and uncoupling protein 1 - with anthropometric, metabolic, and dietary parameters in a Southern Brazilian cohort of 325 children followed up from birth to 4 years old. MATERIALS AND METHODS SNPs were analyzed using polymerase chain reaction-based procedures, and their association with phenotypes was evaluated by t-test, analysis of variance, and general linear models. RESULTS LEPR223Arg allele (rs1137101) was associated with higher daily energy intake at 4 years of age (P = 0.002; Pcorrected = 0.024). PPARG 12Ala-carriers (rs1801282) presented higher glucose levels than Pro/Pro homozygotes (P = 0.007; Pcorrected = 0.042). CONCLUSIONS Two of the six studied SNPs presented consistent associations, showing that it is already possible to detect the influences of genetic variants on susceptibility to overweight in 4-year-old children.

SLC6A14 and 5-HTR2C polymorphisms are associated with food intake and nutritional status in children

BACKGROUND Serotonin plays a critical role in the regulation of food intake. The solute carrier family 6 member 14 (SLC6A14) and serotonin receptor 2C (5-HTR2C) genes are involved in the bioavailability and action of this neurotransmitter. OBJECTIVE Evaluation of the association of six polymorphisms in these genes with food intake and nutritional status in children followed to 7-8years of age. DESIGN Blood samples and the biodemographic data of 344 children were collected at three development stages, in a cross-sectional study undertaken with the cohort from a randomized trial. Polymorphisms were analyzed using polymerase chain reaction-based techniques. RESULTS At 7 to 8years of age, carriers of the A alleles for both the SLC6A14 rs2312054 and SLC6A14 rs12391221 polymorphisms showed higher food intake, except for the sugar-dense food (SDF) intake parameter, than T/T and C/C homozygotes, respectively. Boy carriers of the C allele of rs2071877 had a higher sum of triceps and subscapular folds than T allele carriers at 7 to 8years old. For 5-HTR2C gene variants, A allele carriers (rs3813928) and T allele carriers (rs3813929) had higher food intake at 3 to 4years old than G/G and C/C homozygotes, respectively, except for SDF. At this age, the intake of energy-dense foods was higher in carriers of the T allele (rs3813929) than in C/C homozygotes. CONCLUSION This study provides evidence that genetic variants of these proteins might be involved in the determination of food intake and nutritional status in children.

DBS sampling in imatinib therapeutic drug monitoring: from method development to clinical application

BACKGROUND Imatinib (IM) is widely used in treatment of chronic myeloid leukemia with target trough plasma concentrations above 1000 ng ml(-1). DBS can increase access to IM therapeutic drug monitoring. RESULTS IM was measured in the range 50-4000 ng ml(-1) by UHPLC-MS/MS using one 6 mm DBS in a fully validated method. IM was stable at DBS maintained at 40°C for 36 days. Plasma and DBS concentrations were highly correlated (r > 0.96). The use of a IM concentration target of 765 ng ml(-1) in DBS identified 93% of patients with plasma concentration below 1000 ng ml(-1). CONCLUSION IM can be measured in DBS using UHPLC-MS/MS with results comparable to those obtained in blood plasma.