Within the last decade an intensive research led to an identification of several genes which are involved
in a regulation of energy balance. In most cases, carriers of these gene mutations do not exhibit further
characteristic phenotypic features except for a severe obesity. Obesity based on mutation of one gene
product is called monogenic obesity. Mutations in genes for leptin, leptin receptor, proopiomelanocortin,
prohormone convertase 1, melanocortin 4 and 3 receptor disrupt the physiological humoral signalization
between peripheral signals and the hypothalamic centres of satiety and hunger. Defects of all above
mentioned genes lead to phenotype of abnormal eating behaviour followed by a development of severe
early-onset obesity. Mutations of melanocortin 4 receptor gene represent the most common cause of
monogenic obesity because they are detected in almost 6 % children with early-onset severe obesity.
Mutations of the other genes involved in energy homeostasis are very rare. Although these mutations are
sporadic we assume that further research of monogenic forms of obesity might lead to our understanding
of physiology and pathophysiology of regulation of the energy homeostasis and eating behaviour.
Additionally, they may open new approach to the management of eating behaviour and to the treatment
obesity, gene, leptin, leptin receptor, proopiomelanocortin, prohormone convertase 1,
melanocortin 3 receptor, melanocortin 4 receptor.