Abstract
MicroRNAs (miRNAs) are promising biomarkers for the diagnosis and prognosis of various diseases. Quantitative PCR is the most frequently used method of measuring expression levels of miRNA. However, the lack of validated reference genes represents the main source of potential bias in results. It is normal practice to use small nuclear RNAs as reference genes; however, they often have variable expression. Researchers tend to prefer the most stable reference genes in each experiment. The review includes reference genes for the following tissue types: gliomas, lung cancer, melanoma, gastric cancer, liver cancer, prostate cancer, breast cancer, thyroid cancer, ovarian cancer, cervical cancer, endometrial cancer, rectal cancer, blood tumors, and placental tissues.