Hox gene
Cis acting elements refer to mechanisms that act on the same chromosome they come from, usually either in the same region from which they were produced or a region very close to this origin region. For example, a long non-coding RNA that is produced at one location silences the same or a different location on the same chromosome. Trans acting elements, however, are gene products from one location that act on a different chromosome, either the other in a chromosomal pair, or on a different chromosome from a separate chromosome pair. An example of this is a long non coding RNA from Hox gene C silences Hox gene D on a different chromosome, from a different chromosomal pair.