POMC and hyperinsulinemic hypoglycemia, familial, 4: A de novo heterozygous mutation (c.811C > T, p.R271W) was subsequently detected in the gene encoding POU1FI (PIT1) (11), accounting for his severe GH, TSH, and prolactin deficiencies; however, this could not explain the putative ACTH and gonadotropin deficiencies (8).