IARS1 and heavy chain disease: The qPCR analysis of insulin receptor substrate (irs) genes showed that the expression levels of hepatic irs1 and irs2 were significantly increased in HCD group at 2nd, 4th, and 6th week, but only irs2 was significantly increased at 8th week, compared to those in NCD group (P < 0.05) (Figures 5(a) and 5(b)).