UBC and polycystic ovary syndrome: Among the 89 samples, RNA18S5 and ACTB were the most abundant genes, followed by GAPDH, while the least abundant gene was HMBS. The assessed reference genes showed significant inter-individual variations across the samples, with SD values ranging from 0.54 for RNA18S5 to 1.26 for UBC. Thus it is clear that a vigorous test is required to evaluate the reliability of the 15 candidate reference genes for use as internal controls for comparative gene expression normalization in GCs from PCOS patients.