Schematic representation of the human FBG locus and regulatory regions of the Aα, Bβ, and γ chain genes. FBG Aα, Bβ, and γ chain genes are single copy, and each primary transcript is produced from a single transcription initiation event.2 The FBG locus is found on chromosome 4q23-q32. The genes are drawn approximately to scale (kb bar); however, the scale of the 5′ flanking region of each gene is expanded as noted by the scale bar, which is numbered in bp from +1 to −400/−1400/−3000. The direction of transcription of each gene is indicated by the arrow. The symbol X at the 5′ end of the β chain gene represents the hypothetical location of the putative regulatory region for the coordinated expression of the FBG genes based on earlier studies.31,32,56 The results of this study suggest that further analysis of distal sequences of the 5′ flanking regions of the γ chain gene (X) may aid in elucidation of the mechanism for coordinated induction of the FBG genes in response to IL-6 in extrahepatic tissues. The map of the FBG locus and regulatory elements were derived from other references.^2,28,31,32