Fig 3.

Interactions between genes (A and B) and alleles (1 and 2) in heterozygotes in a diploid individual. Two genes (A and B) located on the same chromosome pair with their respective regulatory regions (crossed boxes) are exhibited here, all at a heterozygous state (haplotypes 1 and 2). Arrows describe the influence of a genomic region on another one: cis‐ and trans‐ acting factors are shown, acting either between genes (dotted lines) or between alleles (solid lines). Enclosed numbers involve different molecular mechanisms described in the text. Depending on the different enhancing and repressing effects and specificity of the target, various departures from additivity in expression levels can be observed in heterozygotes.