RESUMO
OBJECTIVE: To evaluate the association between melanocortin-3 receptor common genetic polymorphisms with childhood obesity and eating behavior in Chilean families. METHODS: Two hundred twenty-nine obese children (6-12 y old, body mass index >95th percentile of Centers for Disease Control and Prevention/National Center for Health Statistics, 2000) and 270 parents were selected. Genotypes for MC3R genetic markers -239A>G, 17C>A (Thr6Lys), 241G>A (Val81Ile), +2138InsCAGACC, and microsatellite D20s32e were determined. Eating behavior scores were computed using the Child Eating Behavior Questionnaire and a shorter version of the Three Factor Eating Questionnaire adapted for evaluating eating inclinations in children. Genotype-obesity associations were assessed by the Transmission Disequilibrium Test. Non-parametric tests were used to compare eating behavior scores across study groups. RESULTS: Allelic frequencies of -239G, 17A, 241A, and +2138InsCAGACC were estimated as 4.5%, 5.9%, 5.6%, and 17.6%, respectively, in obese children. The Transmission Disequilibrium Test in case-parent trios revealed no significant associations between childhood obesity and genetic markers, including the microsatellite D20s32e. In girls, we found significantly higher scores of the emotional eating subscale in carriers of the +2138InsCAGACC compared with non-carriers (P=0.04). In boys, carriers of 17A and 241A showed lower scores for the emotional eating subscale (P=0.01), whereas carriers of +2138InsCAGACC showed significantly lower scores for the enjoyment of food subscale compared with non-carriers (P=0.04). CONCLUSIONS: There is not sufficient evidence to support the contribution for common melanocortin-3 receptor variants in childhood obesity. However, our results are concordant for a role of melanocortin-3 receptor variants in some dimensions of eating behavior such as emotional eating and enjoyment of food.
Assuntos
Alelos , Emoções , Comportamento Alimentar/psicologia , Genótipo , Obesidade/genética , Polimorfismo Genético , Receptor Tipo 3 de Melanocortina/genética , Criança , Chile , Feminino , Marcadores Genéticos , Humanos , Masculino , Repetições de Microssatélites , Obesidade/psicologia , Prazer , Fatores Sexuais , Inquéritos e QuestionáriosRESUMO
It has been proposed that functional mutations in the melanocortin 4 receptor (MC4R) gene have an important impact in body mass index, being considered as a major susceptibility gene for obesity. A number of mutations have been reported in the MC4R gene in subjects from different countries and ethnic groups. However, no reports of MC4R mutations are have been published for South American populations. In this study, DNA samples of thirty-two unrelated obese women of Chilean origin were examined to search for genetic variants in the single exon of the gene through the use of single strand conformational polymorphism techniques and direct sequencing, leading to the identification of a Thr150Ile mutation in heterozygous status. The evaluation of family relatives of the index case for this mutation using PCR-RFLP analysis, identified two additional carriers in a three-generation family. Obesity, eating behavior and body composition phenotypes in this family revealed a possible relation of this variant with obesity in the presence of reduced penetrance. According to our knowledge, this is the first report of MC4R mutations in South American populations.
Assuntos
Comportamento Alimentar/fisiologia , Mutação de Sentido Incorreto/genética , Obesidade/genética , Receptor Tipo 4 de Melanocortina/genética , Adulto , Idoso , Composição Corporal/genética , Índice de Massa Corporal , Criança , Chile , Características da Família , Feminino , Frequência do Gene , Heterozigoto , Humanos , Isoleucina/genética , Masculino , Pessoa de Meia-Idade , Linhagem , Penetrância , Treonina/genéticaRESUMO
OBJECTIVES: A total of 97 apparently healthy subjects were studied in order to establish the influence of smoking habits in studies on neurocardiovascular control and the QTc interval duration. MATERIAL AND METHODS: The study group consisted of 37 smokers and 60 non-smokers as the control. A 12-lead electrocardiogram was performed on all subjects to determine the duration of the QTc interval. Other aspects studied include heart rate variability at rest during 150 cardiac cycles using time domain: coefficient of variation and root mean squared successive difference; and frequency domain: low frequency band (0.04-0.15 Hz) and high frequency band (0.15-0.50 Hz), to determine total energy logarithm and maximum energy frequency. Additionally, conventional cardiovascular autonomic function tests, such as orthostasis, Valsalva maneuver and deep breathing were performed. RESULTS: No significant differences were observed in the duration of the QTc interval nor in time and frequency domain parameters, except in the maximum frequency in the high frequency band, which appeared significantly lower (p < 0.05) in smokers when compared to non-smokers (0.28 +1- 0.1 vs 0.33 +/- 0.1 Hz). No modifications were noted in the cardiovascular autonomic function tests applied to smokers and non-smokers, and the QTc interval was not linked to the rest of the variables studied. CONCLUSIONS: To conclude, smoking habits do not seem to have a significant influence in studies addressed to determine the impact of the autonomic nervous systems on cardiovascular control.