Pitx1 gene is involved in which of the following?

• A. It is the gene identified to be involved in the formation of the pelvic spines in stickleback fish, as well as hind limb development in other vertebrates, such as the mouse.
• B. Pitx1 is involved only in pelvic spines.
• C. Pitx1 is only involved in brain development.
• D. Pitx1 is a gene that inhibits pelvic growth.

Answer: (A)

Pitx1 is a transcription factor that plays a pivotal role in limb development. In many vertebrates, it helps pattern and form the hind limbs. In the stickleback fish, changes in Pitx1 expression in the pelvic region alter whether pelvic spines develop, linking pelvic spine formation to hind limb development seen in other vertebrates such as the mouse. This is why the correct statement recognizes Pitx1 as involved in both pelvic spine formation and hind limb development. It’s not limited to pelvic spines, it isn’t primarily a brain-development gene, and it doesn’t act as an inhibitor of pelvic growth.