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Non-Alcoholic Fatty Liver Disease (NAFLD) is a spectrum of liver diseases that encompass steatosis, Non-Alcoholic Steatohepatitis (NASH) and fibrosis. It is a major public health problem due to its frequency and potential complications (cirrhosis, hepatocellular carcinoma). At present, the monitoring of patients with steatosis or NASH is not fully coded and current treatments are not very effective. Research into the genetics and epigenetics of NAFLD is booming. While genetics studies modifications into the nucleotide sequence of genes, epigenetics studies modifications in the function of a gene that cannot be explained by alterations to the gene sequence. PNPLA3, TM6SF2 and MBOAT7-TMC4 are the 3 main genes for which single nucleotide polymorphisms are associated with steatosis, NASH and hepatic fibrosis, independently of insulin resistance and metabolic syndrome. MicroRNAs (miR), small non-coding RNAs inhibit messenger RNAs and thus regulate gene expression. The expression of some miRs in the liver is modified in NAFLD: miR 122 is decreased and miR 34a is increased. Some miRs are also found in the circulation: for example, miR 122 is increased in the case of NAFLD. Finally, the methylation of target genes is modified in NAFLD resulting in changes in their expression. This is particularly the case for PPAR, a key gene for lipid metabolism. In future, it is likely that substantial genetic and epigenetic data can be obtained for each individual from a simple blood sample allowing personalized monitoring and treatment for NAFLD, as for other diseases. [ABSTRACT FROM AUTHOR]

Non-alcoholic fatty liver disease (NAFLD) is a major health problem which is now recognized by governmental agencies. NAFLD is a spectrum of diseases including non-alcoholic fatty liver (NAFL), non-alcoholic steatohepatitis (NASH) and its complications: fibrosis, cirrhosis and hepatocellular carcinoma. Worldwide, 25% of the general population have NAFL, and 1.5 to 6.5% have NASH. These high frequencies are linked to the epidemic of overweight and obesity. As for obesity, NAFLD is a complex and heterogeneous disease. The mechanisms, the clinical occurrence, the associated diseases and the natural history imply multiple genetic and environmental factors. Insulin-resistance may play a central but not exclusive role in the occurrence of NASH. NAFLD such as obesity and type 2 diabetes is a multisystem disease associated with various complications (cardio-vascular events, hepatic and extra hepatic cancers, chronic kidney disease. . .). Advances in the knowledge of the mechanisms of NAFLD led to the development of new pharmacological or non pharmacological treatments, which are undergoing clinical trials. The management of patients with NAFLD must be well structured, particularly because the liver biopsy, which is still the gold standard, cannot be performed in all suspected subjects. There is a need to develop and validate new non-invasive tools based on analyses of serum or on physical assessment that allow reliable assessment of fibrosis, the NASH and steatosis. Their availability will allow easy screening, diagnosis and follow-up of patients. [ABSTRACT FROM AUTHOR]