|Mutations in SH3BP2 cause cherubism|
June 11, 2001
Researchers have found genetic defects that cause cherubism. The mutations occur in the SH3-binding protein SH3BP2, an important molecule in cell signaling. Mutations in just one copy of the gene are sufficient to cause the disease.
Cherubism is characterized by severe bone degradation of both the upper and lower jaws beginning at about age three. The bone loss is followed by the accumulation of fibrous tissue that causes facial swelling especially around the cheeks, hence the disease's name.
The researchers studied 15 families in which 66 people were diagnosed with cherubism. In 12 of the families the mutations occurred in the SH3BP2 gene, located on chromosome 4. Seven unique point mutations, each causing an amino acid substitution, were isolated. These mutations were not found in 200 controls without the disease.
In the remaining three families the protein-coding region of the SH3BP2 gene appeared normal and no mutations could be isolated.
The scientists conclude that, because the consequences of this gene defect are restricted to the jaws, SH3BP2 may play a role in dental development in children, possibly regulating the balance between bone formation and loss, which is essential for tooth eruption.
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