The Role of Fat Mass and Obesity Associated Gene (Fto) in Satiety and Binge Eating Disorder

Abstract

Obesity is a major health problem and one of the biggest predictors of the development of chronic diseases. Variations in the Fat mass and obesity associated gene (FTO) have been shown to associate strongly with obesity. Among patients with severe obesity, there is a subpopulation that presents an eating disorder known as Binge Eating Disorder. Because of its expression in the hypothalamus, FTO could be associated with modulation of satiety and, perhaps, play a role in the genesis of BED, contributing to severe obesity. A search in PubMed was carried out with the following terms: Morbid Obesity AND FTO, FTO AND Satiety Response, Binge Eating Disorder AND FTO. No restriction on the date of publication, language or type of design was applied. Sixteen articles were found. Twelve were related to FTO and grade III obesity, and three were related to FTO and satiety. Ten studies were excluded. Thus, six articles were evaluated in this review. The scarce literature limits further conclusions about the potential impact of the associations with FTO in the treatment of obesity, but all articles included in this revision show association with at least one SNP of FTO. Further studies are required to clarify these associations, especially in relation to rs9939609 (A/T), because, up to this moment, it seems to be the one variant with greatest impact on obesity in humans. Keywords: Obesity; FTO; satietyObesity is one of the main health problems in the 21st Century. It is an established risk factor for conditions such as Type 2 diabetes mellitus, cardiovascular disease and cancer 1 .The prevalence of overweight and obesity has doubled in the last thirty years. In Brazil, a 2008/2009 survey of the Ministry of Health showed that 8.9% of the population is obese. In the South of the country, 10.1% of the male population and 15.1% of the female population is obese. Brazilian estimates point out that, in the year 2025, the country will have the fifth largest prevalence of obesity worldwide 2 . Clinically, obesity is diagnosed in the presence of a body mass index (BMI) equal to or higher than 30 kg/m 2 , in adults 3 .Recent studies show associations of BMI with body fat and with the the "Fat mass and obesity associated" (FTO) gene 4 , located in chromosome 16q12.2 5,6 . Variations in this gene (single-nucleotide polymorphisms -SNPs) were strongly associated with obesity and diabetes mellitus 7 . The association of FTO with human obesity has been shown in caucasian populations studies [8][9][10][11] . Besides the association with BMI and higher risk for overweight and obesity, SNPs in FTO have been associated with obesity and body weight 5,8,11 , leptin levels 11 , subcutaneous fat 5,8 , fat mass 5,8,11 and waist circumference 11 .The messenger RNA (mRNA) of FTO is expressed in the hypothalamus 12 , an area that is connected with appetite regulation; in rodents, FTO mRNA expression in the hypothalamus is modulated by acute food deprivation 13 . One recent study, in human adults, has found differences in the caloric intake, but...

Genetic variants in the fat mass and obesity-associated (FTO) gene confer risk for extreme obesity and modulate adiposity in a Brazilian population

“…Moreover, there are only few studies associating FTO variants and extreme obesity, since sample selection is difficult and requires considerable effort. The strategy of using an extreme phenotype sample probably increases the power for detecting genetic associations in a median sample size (Price et al, 2008;Castro et al, 2015).…”