Significance of Circulating Cell-Free DNA Species in Non-Alcoholic Fatty Liver Disease.

The pathogenetic mechanisms involved in the progression of non-alcoholic fatty liver disease (NAFLD) have not been completely elucidated, while the significance of circulating cell-free DNA (cf-DNA) species has been rarely evaluated in NAFLD. Herein, we assessed the serum levels of cf-DNA species in NAFLD patients and investigated their potential associations with patients' characteristics and severity of liver disease. Forty-nine adult patients with NAFLD of any stage were included in this cohort study. Cf-DNA was isolated from patients' sera and the levels of several distinct cf-DNA species including total cf-DNA, gene-coding cf-DNA, Alu repeat sequences, mitochondrial DNA copies and 5-methyl-2'-deoxycytidine were determined. Cirrhotic compared to non-cirrhotic patients had significantly lower serum levels of cf-DNA and RNAse P coding DNA as well as higher expression of 5-methyl-2'-deoxycytidine. After adjustment for the significant clinico-epidemiological factors, lower serum levels of cf-DNA or RNAse P were independently associated with the presence of cirrhosis. Serum levels of total and gene-coding DNA are associated with the presence of cirrhosis in NAFLD patients regardless of clinical or epidemiological parameters and may therefore be used as a screening tool for NAFLD progression.