The PITX1 gene happens to turn on one of these genes, TBX4?

The PITX1 gene happens to turn on one of these genes, TBX4 = The PITX1 gene is like a switch, and the gene TBX4 is like a lamp; it is a coincidence that geng PITX1 acts as the promoter gene for the gene TBX4, that is: the former turns on the latter?

Context:



"There are two genes known to be involved in limb development that are located within the chromosome 17 region," Gurnett says. "The PITX1 gene happens to turn on one of these genes, TBX4. Both genes play a role in leg development, but are not involved in development of the arm, explaining why clubfoot only affects the leg. We're starting to understand the genetic pathway by which clubfoot develops, and we think that it is an abnormality of very early limb development, probably in the first trimester of pregnancy."


http://www.sciencedaily.com/releases/2010/07/100701131205.htm