KLF1 and Infertility: Our observations, in addition to the SPINK2 data and data related to infertility (i.e. P1/P2 protamines, Pde8b, Trim28, Tcfl5), and to the other diseases (i.e. PIKFYVE in cataract, NFIA, SCN1A in neurological or epilepsy disturbances, KLF1 in hemoglobin persistence, NR5A2 in pancreatic cancer), seem to confirm that the severity of the phenotype depends on the gene expression level (Jodar and Oliva, 2014; Tan et al., 2020; Leal et al., 2021; Sandhu et al., 2021; Heshusius et al., 2022; Mei et al., 2022; Ogura et al., 2022; Valassina et al., 2022; Xu et al., 2022).