KDM6A and hyperinsulinism: Endocrine abnormalities were seen in 38.3% of patients with pathogenic KDM6A. Specifically, we detected a lower frequency of premature thelarche (6.4%) when compared with previous studies (25–43%).30,31,37 A higher prevalence of neonatal hypoglycemic (56.4% of the overall cohort) and hyperinsulinism (27.7%) were detected in our cohort.