Figure 12.

The promoter region of the human factor IX gene showing the androgen response element (ARE) and the regions implicated in binding LF-A1/HNF4, C/EBP. Coordinates are relative to the transcription start site (+1). Haemophilia B Leyden mutations (closed arrows) lie outside the ARE but within the LF-A1/HNF4 and C/EBP regions implicated in constitutive expression. In contrast, the promoter mutation G-26C (haemophilia B Brandenburg, open arrow) causes lifelong haemophilia B and lies within both the ARE and the −9 to −40 region associated with constitutive expression.