[Pituitary specific transcription factor Pit-1/GHF-1 and combined pituitary hormone deficiency]

Pit-1/GHF-1 is a pituitary-specific POU-domain DNA binding factor, which binds to, and trans-activates the promoters of both growth hormone (GH) and prolactin (PRL) genes. It is well conserved among vertebrates and is indispensable for both differentiation and proliferation of the somatotrophs, lactotrophs and thyrotrophs. PIT1 abnormality is defined as a genetic abnormality in the PIT1 gene, and results in various types of combined deficiencies of thyrotropin (TSH), GH, and PRL. PIT1 abnormality was first recognized as an excellent model for 'transcription factor disease'. Recently, we found a novel case whose cannot be explained by the PIT1 gene mutation alone. Such case will give us precious clue to identify modifier factors of Pit-1/GHF-1.