Expression of common housekeeping genes is affected by disease in human hepatitis C virus-infected liver

Background Comparative gene expression is commonly determined with reference to the expression of a housekeeping gene (HKG), the level of which is assumed to be unregulated. There are little data to date on the effect of disease on the expression of classic HKGs in hepatitis C virus (HCV)-infected human liver. Aims To identity HKGs stable across a wide spectrum of disease in human HCV-infected liver. Methods beta-Actin, hypoxanthine phosphoribosyltransferase 1 (HPRT1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), splicing factor arginine/serine-rich 4, beta-glucuronidase and 18S ribosomal RNA (18S rRNA) were measured by real-time polymerase chain reaction in liver biopsy tissue. Samples were categorised for inflammation, fibrosis and steatosis, and allocated into groups with mild or severe liver disease. Values were analysed using Spearman's rank correlation, NormFinder, BestKeeper and geNorm programs. Results All genes performed well in the samples of patients with low disease activity, but HPRT1, beta-actin, GAPDH and 18S rRNA ranked poorly in samples with severe fibrosis or inflammation. Conclusions Our results indicate that liver disease affects the expression of common HKGs and that beta-glucuronidase and splicing factor arginine/serine-rich 4 are the most stable HKGs from this group for studies of gene expression in HCV-infected human liver.