PROP1 and hypopituitarism: Anomalies of the classic transcription factor genes cause very specific profiles of hormone deficiencies due to abnormal pituitary development; the most prevalent defects in patients with growth failure are in PROP1, which was reported in a literature analysis to occur in 6.7% of worldwide sporadic cases of combined pituitary hormone deficiency and 11.2% when familial cases were included (21).