The study demonstrates that the CatSper current (ICatSper) induced by intracellular alkalization, can be reversibly inhibited by HC056456, thereby replicating the phenotype of CatSper deficiency in both HC056456-treated human and mouse sperm (Carlson et al., 2009). This evidence concerns the gene CATSPER1 and hyperinsulinemic hypoglycemia, familial, 4.