YWHAZ and polycystic ovary syndrome: The Sadek study demonstrated that GAPDH is relatively unsuitable for the normalization of endometrial tissue from polycystic ovary syndrome and normal women of reproductive age, whereas YWHAZ (tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta), CYC1 (cytochrome c-1), and ACTB showed acceptably small variation in expression across these two conditions [14].