PNPLA3 and TM6SF2 polymorphisms in Brazilian patients with nonalcoholic fatty liver disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is becoming the most common chronic liver disease worldwide, with significant morbidity associated with nonalcoholic steatohepatitis (NASH). Genome-wide association studies demonstrated that the variants rs738409 C/G in the PNPLA3 and rs58542926 C/T in the TM6SF2 genes are determinants of inter-individual and ethnicity-related differences in hepatic fat content and NAFLD progression. AIM: To investigate PNPLA3 and TM6SF2 genotype frequency and their association with NAFLD development and progression in Brazilian patients. METHODS: This cross-sectional case-control study enrolled 285 individuals from the Gastroenterology and Hepatology clinics at a university hospital in Brazil. The case patients (n = 148) were confirmed to have NAFLD by the identification of hepatic steatosis on ultrasonography and exclusion of other causes of liver disease. According to the clinical protocol, patients underwent liver biopsy when at high risk for NASH and/or advanced fibrosis (n = 65). Steatohepatitis was confirmed in 54 patients. Individuals who did not have biopsy indication or NASH on histology were considered to have simple steatosis (n = 94). The control group (n = 137) was selected among patients that attended the Intestinal Disease clinic and was composed of subjects without abnormalities on abdominal ultrasonography and normal liver biochemical tests. All individuals underwent PNPLA3 and TM6SF2 genotype analysis. RESULTS: PNPLA3 CC, CG and GG genotype frequencies were 37%, 44% and 19%, respectively, in NAFLD patients and were 58%, 31% and 10% in controls (P < 0.001). In a model adjusted for gender, age, body mass index and type 2 diabetes mellitus, the G allele increased the chance of NAFLD (OR = 1.69, 95%CI: 1.21-2.36, P = 0.002) and NASH (OR = 3.50, 95%CI: 1.84-6.64, P < 0.001). The chance of NASH was even higher with GG homozygosis (OR = 5.53, 95%CI: 2.04-14.92, P = 0.001). No association was found between G allele and the features of metabolic syndrome. In histological assessment, PNPLA3 genotype was not associated with steatosis grade, although GG homozygosis increased the chance of significant NASH activity (OR = 17.11, 95%CI: 1.87-156.25, P = 0.01) and fibrosis (OR = 7.42, 95%CI: 1.55-34.47, P = 0.01) in the same adjusted model. TM6SF2 CC, CT and TT genotype frequencies were 83%, 15% and 0.7%, respectively, in NAFLD patients and were 84%, 16% and 0.7% in controls (P = 0.78). The T allele presence was not associated with NAFLD or NASH, and was not associated with histological features. CONCLUSION: PNPLA3 may be involved in susceptibility and progression of NAFLD and NASH in the Brazilian population. More advanced histological liver disease was associated with the G allele. The TM6SF2 genetic variants were not associated with NAFLD susceptibility and progressive histological forms in the population studied, but further studies are required to confirm these findings.

Lack of association between genetic polymorphism of FTO, AKT1 and AKTIP in childhood overweight and obesity / Falta de associação entre o polimorfismo genético do FTO, AKT1 e AKTIP e o sobrepeso e a obesidade infantis

Abstract Objective: Obesity is a chronic disease caused by both environmental and genetic factors. Epidemiological studies have documented that increased energy intake and sedentary lifestyle, as well as a genetic contribution, are forces behind the obesity epidemic. Knowledge about the interaction between genetic and environmental components can facilitate the choice of the most effective and specific measures for the prevention of obesity. The aim of this study was to assess the association between the FTO, AKT1, and AKTIP genes and childhood obesity and insulin resistance. Methods: This was a case-control study in which SNPs in the FTO (rs99396096), AKT1, and AKTIP genes were genotyped in groups of controls and obese/overweight children. The study included 195 obese/overweight children and 153 control subjects. Results: As expected, the obese/overweight group subjects had higher body mass index, higher fasting glucose, HOMA-IR index, total cholesterol, low-density lipoprotein, and triglycerides. However, no significant differences were observed in genes polymorphisms genotype or allele frequencies. Conclusion: The present results suggest that AKT1, FTO, and AKTIP polymorphisms were not associated with obesity/overweight in Brazilians children. Future studies on the genetics of obesity in Brazilian children and their environment interactions are needed.

Resumo Objetivo A obesidade é uma doença crônica sustentada por fatores ambientais e genéticos. Estudos epidemiológicos documentaram que maior ingestão de energia e um estilo de vida sedentário, bem como a contribuição genética, são forças por trás da epidemia de obesidade. O conhecimento sobre a interação entre os componentes genéticos e ambientais pode facilitar a escolha das medidas mais efetivas e específicas para a prevenção da obesidade. O objetivo deste estudo foi avaliar a relação entre os genes associado à massa de gordura e à obesidade (FTO), homólogo 1 do oncogene viral v-akt de timoma murino (AKT1) e de ligação AKT1 (AKTIP) e a obesidade infantil e a resistência à insulina. Métodos Estudo de caso-controle no qual os polimorfismos de nucleotídeo simples (SNPs) nos genes FTO (rs99396096), AKT1 e AKTIP foram genotipados em grupos de controle e de crianças obesas/acima do peso. Foram recrutadas 195 crianças obesas/acima do peso e 153 indivíduos controle. Resultados Como esperado, os indivíduos do grupo obeso/acima do peso apresentaram maior índice de massa corporal, maior glicemia de jejum, índice do modelo de avaliação de homeostase (HOMA-IR), colesterol total, lipoproteína de baixa densidade e triglicerídeos. Contudo, não encontramos diferenças significativas no genótipo de polimorfismos gênicos ou nas frequências alélicas. Conclusão Nossos resultados sugerem que os polimorfismos AKT1, FTO e AKTIP não estavam associados à obesidade/sobrepeso em crianças brasileiras. São necessários estudos futuros sobre a genética da obesidade em crianças brasileiras e suas interações ambientais.

Lack of association between genetic polymorphism of FTO, AKT1 and AKTIP in childhood overweight and obesity.

OBJECTIVE: Obesity is a chronic disease caused by both environmental and genetic factors. Epidemiological studies have documented that increased energy intake and sedentary lifestyle, as well as a genetic contribution, are forces behind the obesity epidemic. Knowledge about the interaction between genetic and environmental components can facilitate the choice of the most effective and specific measures for the prevention of obesity. The aim of this study was to assess the association between the FTO, AKT1, and AKTIP genes and childhood obesity and insulin resistance. METHODS: This was a case-control study in which SNPs in the FTO (rs99396096), AKT1, and AKTIP genes were genotyped in groups of controls and obese/overweight children. The study included 195 obese/overweight children and 153 control subjects. RESULTS: As expected, the obese/overweight group subjects had higher body mass index, higher fasting glucose, HOMA-IR index, total cholesterol, low-density lipoprotein, and triglycerides. However, no significant differences were observed in genes polymorphisms genotype or allele frequencies. CONCLUSION: The present results suggest that AKT1, FTO, and AKTIP polymorphisms were not associated with obesity/overweight in Brazilians children. Future studies on the genetics of obesity in Brazilian children and their environment interactions are needed.

Association between tryptophan hydroxylase-2 gene and late-onset depression.

OBJECTIVE: The aim of this study was to examine the association between polymorphisms (SNP) in the tryptophan hydroxylase-2 (TPH2) gene and late-onset depression (LOD) in the Brazilian population. METHODS: We genotyped 8 tag SNPs in the TPH2 gene in 84 outpatients with LOD and 79 individuals belonging to the comparison group to investigate an association between the TPH2 gene and LOD. RESULTS: Our findings suggested an association between tag SNP rs4565946 heterozygous C/T (p = 0.034; χ2 = 6.7; df = 2) and decreased risk of LOD. The tag SNP rs11179000 ancestral homozygous A/A (p = 0.025; χ2 = 7.3; df = 2) and increase risk of LOD and allelic association of ancestral allele A and increase risk of LOD was demonstrated (p = 0.005; χ2 = 7.8; df = 1). CONCLUSION: We found the statistically significant association between two tag SNPs and LOD. Our results support the hypothesis that the TPH2 gene is associated with LOD.