22q11.2 deletion syndrome

All of us have 46 chromosomes in total, which are carry our genes and tell us how to grow and develop. Chromosomes are typically arranged into 23 pairs and labeled 1-22 based on size with the last pair (XX or XY) determining if we are male or female. In 22q11.2 deletion syndrome, there is a small piece missing on one of the number 22 chromosomes. That deletion is located on the long arm of the chromosome at a location designated as 22q11.2.

We are still learning about the purpose of each of the genes from that deleted region on chromosome 22. One gene deleted is TBX1 and researchers believe that when missing, it can lead to heart defects, openings in the roof of the mouth (cleft palate), hearing loss, low calcium levels in the blood, and the similar facial features often found in people with 22q11.2 deletion syndrome. The increased risk for behavior problems and mental illness may be due to the loss of another gene on the 22nd chromosome, called COMT. The loss of other genes in this region is what likely causes the other varied features of 22q11.2 deletion syndrome.