SH3BP2

The SH3BP2 gene provides instructions for making a protein whose exact function is unclear, although it is known to interact with other proteins within cells. The SH3BP2 protein plays a role in transmitting chemical signals, particularly in certain immune system cells and cells involved in the replacement of old bone tissue with new bone (bone remodeling).

Studies suggest that the SH3BP2 protein helps regulate signaling pathways that activate immune system cells called B cells and macrophages. The protein is also involved in the production of osteoclasts, which are specialized cells that break down bone tissue when it is no longer needed. Osteoclasts play a central role in bone remodeling.

cherubism - caused by mutations in the SH3BP2 gene

At least 11 mutations in the SH3BP2 gene have been identified in people with cherubism. Each of these mutations changes a single protein building block (amino acid) in a critical region of the SH3BP2 protein. These genetic changes lead to the production of an overly active version of this protein. The effects of SH3BP2 mutations are still under study, but researchers believe that the abnormal protein alters critical signaling pathways in cells associated with the maintenance of bone tissue and in certain immune system cells. The overactive protein likely causes inflammation in the bones of the jaw and triggers the production of an increased number of osteoclasts. An excess of these bone-eating cells contributes to the abnormal breakdown of bone tissue in the upper and lower jaws. A combination of bone loss and inflammation likely underlies the cyst-like growths characteristic of cherubism.