The body mass of an individual organism depends on both genetic and environmental factors. Conditions such as obesity or being underweight largely depend on food, exercise or the presence of a disease. However, obesity can be the result of genetic factors. In mice, a mutation on chromosome 7 causes the pattern of fat deposition to be altered. The gene interacts with other genes to dysregulate the energy balance of the mouse and the mouse can grow up to 50% fatter than a normal mouse.