A model for the callipyge polar overdominance. The expression profile of DLK1, GTL2, PEG11 and MEG8 are illustrated for +/+, CLPGM/+P, +M/CLPGP and CLPG/CLPG individuals. The +M/CLPGP individuals expressing the callipyge phenotype are boxed in red. Genes transcribed in the cen to ter direction are represented as blue arrows. The thickness of the arrows reflects the transcription level. The identified cis effects are illustrated by the thick black arrows connecting the hypothetical located of the CLPG mutation and the influenced genes. The putative trans effects are likewise illustrated by the thin, dashed arrows.
Source: Charlier, C. et al. The callipyge mutation enhances the expression of coregulated imprinted genes in cis without affecting their imprinting status. Nat Genet 27, 367-369 (April 2001).