PLCZ1 and Infertility: However, despite the fact that some fertile controls can exhibit similar levels of PLCZ1 expression to infertile patients, immunofluorescence analyses have clearly confirmed that the relative fluorescence (RF) intensity of PLCZ1 in human sperm is significantly lower in OAD patients than in fertile males (Heytens et al. 2009, Kashir et al. 2013), thus providing us with the capability to perform diagnostic assays.