HMOX1 and anemia: Additionally, HO-1-KO tests have the following problems: partial lethality during prenatal development; infertility; smaller size of the HO-1-KO mice relative to wild-type mice; development of microcytic normochromic anemia in HO-1-KO animals; iron deposition in organs, such as the liver and kidneys, which can affect the results of the experiments (Agarwal and Nick, 2000; Gozzelino et al., 2010).