Non-alcoholic fatty liver disease and metabolic syndrome in adolescents: pathogenetic role of genetic background and intrauterine environment

In the last three decades the incidence of metabolic syndrome (MetS) has been growing worldwide along with an increase of obesity, type 2 diabetes mellitus, and non-alcoholic fatty liver disease (NAFLD). In children and adolescents such epidemics are particularly worrisome, since the metabolic consequences in adulthood will significantly burden the health care system. Although the definition of MetS in childhood is still controversial, there is agreement with respect to NAFLD being the hepatic manifestation of MetS. However, the molecular pathogenesis of MetS and its contribution to NAFLD is complex and closely related to the pre- and postnatal environment as well as to genetic predisposing factors. The analysis of the possible relationships between NAFLD and MetS is particularly interesting, not only from an epidemiological point of view, but also to better understand the genetic and environmental factors contributing to the development of both diseases. We here summarize the most recent epidemiological data on the incidence of both diseases in adolescents, and several aspects linking MetS with NAFLD, discussing the possible role played by genetics and intrauterine environment.