POU1F1 and hypopituitarism: Another limitation is the fact that the CPHD-nonPROP1 group consists of highly heterogeneous genetic disorders, i.e., mutations of many transcription factors expressed early in pituitary organogenesis resulting in syndromic hypopituitarism and mutations of POU1F1 (Pit1), which, as with Prophet of Pit1 (PROP1), are expressed at a later stage of pituitary organogenesis and result in non-syndromic hypopituitarism.