Background: Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are the most common
markers of liver damage, but serum level interpretation can be complicated. In hepatocytes, microRNA-122 (miR-122) is
the most abundant miRs and its high expression in the serum is a characteristic of liver disease.
Objective: We aimed to compare the circulatory level of miR-122 in patients with chronic hepatitis C (CHC), hepatitis C
virus (HCV) infected liver transplant candidates (LTC) and healthy controls to determine if miR-122 can be considered as
an indicator in chronic and advanced stage of liver disease.
Method: MiR-122 serum level was measured in 170 interferon-naïve (IFN-naïve) CHC patients, 62 LTC patients, and 132
healthy individuals via TaqMan real-time PCR. Serum levels of miR-122 were normalized to the serum level of Let-7a
and miR-221. Also, the ALT and AST levels were measured.
Results: ALT and AST activities and the expression of circulatory miR-122 were similar in the CHC and LTC groups, but
it had significantly increased compared to healthy individuals (P<0.001 and P<0.001, respectively). Up-regulation of miR122 in the sample of patients with normal ALT and AST activities was also observed, indicating that miR-122 is a good
marker with the high sensitivity and specificity for diagnosing liver damage.
Conclusion: miR-122 seemed to be more specific for liver diseases in comparison with the routine ALT and AST liver
enzymes. Since the lower levels of circulating miR-122 were observed in the LTC group compared to CHC group,
advanced liver damages might reduce the release of miR-122 from the hepatocytes, as a sign of liver function deficiency.