PROP1 and hypopituitarism: Central congenital hypothyroidism in association with combined pituitary hormone deficiencies may be i) syndromic, resulting from mutations in early transcription factors, and associated with developmental abnormalities (eg septo-optic dysplasia and its variants, holoprosencephaly and midline defects, ocular or skeletal defects, and intellectual impairment) or ii) non syndromic resulting from mutations in late transcription factors (PROP1, POU1F1).