Epidemiology and Natural History of NAFLD.

Paralleling the growing prevalence of obesity and metabolic syndrome, nonalcoholic fatty liver disease (NAFLD) is emerging as the most frequent hepatopathy in adults and children. The true prevalence of pediatric NAFLD is still unknown, because of the heterogeneity of diagnostic methods used for diagnosis in the available studies and the different characteristics of the populations evaluated. Pediatric NAFLD is typically of primary origin and it is strongly associated with several features of the metabolic syndrome. Age, gender and race/ethnicity are significant determinants of risk, and sex hormones, insulin sensitivity and adipocytokines are implicated in the pathogenesis of pediatric NAFLD. The natural history of NAFLD in children is still poorly understood, because of its complex nature and the scarcity of prospective studies, especially in pediatric populations. Both genetic and environmental factors seem to be implicated in the development and progression of the disease via multiple mechanisms that involve liver crosstalk with other organs and tissues, especially gut and adipose tissue. To evaluate and effectively treat pediatric NAFLD, the pathophysiology and natural history of the disease should be clarified and noninvasive methods for screening, diagnosis, and longitudinal assessment developed.