Additional major features frequently seen in AR STAT5B deficiency such as hyperprolactinemia13 were detected in only a few of our AD STAT5B subjects (mother and aunt of family 2; Proband 3), and extrapulmonary autoimmune disease41 was diagnosed only in Proband 3 (thyroiditis and celiac disease). Here, STAT5B is linked to hyperinsulinemic hypoglycemia, familial, 4.