Predisposition to obesity

# Is obesity in the genes? Overweight and obesity are among the most pressing health problems in industrialized countries. Overweight is defined as a BMI (Body Mass Index) of over 25, obesity as a BMI of 30 or more. According to Statistics Austria, around 40% of the population in Austria over the age of 15 are overweight and around 17% of these are obese. By the age of eight, every third boy and every fourth girl is overweight or obese. > The BMI is calculated by dividing your current weight in kg by your height in meters squared: > > BMI = kg/m2. There are many reasons for being overweight and, to a certain extent, obesity is also genetic. Genes can have a significant influence not only on the storage of fat, but also on eating behavior. This involves the hunger and satiety effect, self-discipline, snacking behavior and much more. Nevertheless, genetics is only part of the overall picture and external factors such as lifestyle, social environment, sport and diet are at least as important for a healthy body weight. > ## It runs in the family... > > Experts believe that in the case of obesity, i.e. severe or pathological overweight, genetics plays a decisive role in addition to environmental influences (epigenetics). > > - Lifestyle (exercise, diet) > - chronic stress > - mental illnesses > - depression, mental instability > - Eating disorders > - Hormonal disorders > - Medication > - Eating behavior # What does genetics have to do with it? We are investigating four genes with an influence on BMI, overweight and obesity: The FTO gene (fat mass and obesity gene) is one of the best-known genes for the expression of overweight and obesity. Among other things, the gene regulates body weight and fat metabolism and influences appetite. It has been shown that the FTO gene in the hypothalamus, a part of the brain, is highly active after food deprivation and leads to an increased consumption of high-calorie foods. - Variant rs9935401 of the FTO gene: Genotypes A/G and A/A show an increased risk of obesity. Genotype G/G shows a normal high risk. - Variant rs9939609 of the FTO gene: Genotypes A/A and A/T show an increased risk of obesity. The genotype T/T shows a normal high risk. - Variant rs1121980 of the FTO gene: Genotypes A/A and A/G show an increased risk of obesity. The G/G genotype shows a normal high risk. The TMEM18 gene (transmembrane protein 18A gene) is associated with the regulation of body weight and body fat percentage. For example, some genetic variants of the gene are associated with increased storage of body fat and resulting obesity. Other variants are associated with a low BMI. - Variant rs6548238 of the TMEM18 gene: Genotypes C/T and T/T show a low BMI and a low predisposition to obesity. The C/C genotype shows a normal BMI. The MC4R gene (melanocortin 4 receptor gene) carries the blueprint for the receptor of the same name in the cells. This is primarily involved in the central nervous system in controlling the hunger and satiety mechanism. When the receptor is activated, the appetite or feeling of hunger decreases and food intake is optimally stopped. The receptor works closely with leptin, a messenger substance from the fat cells, which also has an appetite-inhibiting effect. MC4R deficiency is the most common cause of inherited obesity identified to date. - Variant rs17782313 of the MC4R gene: Genotypes C/C and C/T show a high risk of obesity, with genotype C/C being slightly more at risk. The T/T genotype, on the other hand, carries a normal risk and therefore does not appear to be at risk. The SH2B1 gene (SH2B adaptor protein 1 gene) influences appetite regulation, energy consumption and fat metabolism. It interacts with various hormones and signaling pathways involved in body weight control, including leptin and insulin. Leptin is a messenger substance from the fat cells that transmits the degree of filling of the fat stores to the brain. The SH2B1 gene influences these transmission processes in the brain and can thus control the feeling of hunger and satiety. Thus, variations of the gene are associated with obesity, just as a complete loss of function of the gene is associated with severe and early-onset obesity. - Variation rs7498665 of the SH2B1 gene: Genotypes A/G and G/G show an increased risk of obesity and an increased BMI. Genotype A/A, on the other hand, shows a normal BMI.