HNF1BHNF1 homeobox B, also known as HNF1B or transcription factor 2, is a human gene.FunctionHNF1B encodes hepatocyte nuclear factor 1-beta, a protein of the homeobox-containing basic helix-turn-helix family. The HNF1B protein is believed to form heterodimers with another member of this transcription factor family, HNF1A; depending on the HNF1B isoform, the result may be to activate or inhibit transcription of target genes. Deficiency of HNF1B cause abnormal maternal-Zygote transition and early embryogenesis failure. Mutation of HNF1B that disrupts normal function has been identified as the cause of MODY 5. A third human transcript variant is believed to exist based on such a variant in the rat: however, to date such an mRNA species has not been isolated.