Interestingly, we developed a more robust bioassay that permits the classification of ‘PLCZ1 deficiency’ by incorporating the combination of mean PLCZ1 level and the specific proportion of sperm in a given patient sample exhibiting PLCZ1 (Meng et al. 2020). The gene discussed is PLCZ1; the disease is hyperinsulinemic hypoglycemia, familial, 4.