Херубизм: Генетическое заболевание костей лица

Cherubism is a rare genetic disorder that causes prominence in the lower portion in the face. The name is derived from the temporary chubby cheeked resemblance to putti, the chubby faced infants featured in Renaissance paintings, which were often mistakenly described as cherubs.

The appearance of people with the disorder is caused by a loss of bone in the mandible which the body replaces with excessive amounts of fibrous tissue. In most cases, the condition fades as the child grows, but in rare cases the condition continues to deform the affected person's face. Cherubism also causes premature loss of the primary teeth and lack of eruption and or displacement of the permanent teeth. Cherubism is a rare autosomal dominant disease of the maxilla and mandible. Approximately 200 cases have been reported by medical journals with the majority being males. Cherubism is usually first diagnosed around age seven and continues through puberty and may or may not continue to advance with age. Degrees of cherubism vary from mild to severe. Osteoclastic and osteoblastic remodeling contributes to the change of normal bone to fibrous tissue and cyst formation. As noted by the name, the patient's face becomes enlarged and disproportionate due to the fibrous tissue and atypical bone formation. The sponge like bone formations lead to early tooth loss and permanent tooth eruption problems. The condition also affects the orbital area, creating an upturned eye appearance. The cause of cherubism is believed to be traced to a genetic defect resulting from a mutation of the SH3BP2 gene from chromosome 4p16.3. While the condition is rare and painless, the afflicted suffer the emotional trauma of disfigurement. The effects of cherubism may also interfere with normal jaw motion and speech. Currently, removal of the tissue and bone by surgery is the only treatment available. This condition is also one of the few that unexpectedly stops and regresses. Normal bone remodeling activity may resume after puberty. Cherubism is displayed with genetic conformation and when excessive osteoclasts are found in the affected areas of the mandible and maxilla. Large cysts will be present with excessive fibrous areas inside the bone. The fibers and cysts will be found among the trabecula of the Coronoid process, the ramus of mandible, the body of mandible and the maxilla regions. The maxilla will be affected up to and including the orbits and sometimes inside the lower orbits. The maxilla and zygomatic bones are depressed and eyes appear to gaze upward. The maxilla has been found to be more severely affected in most cases than the mandible bone. Some patients found with lower inner orbital growths and cysts may lose vision.

Cherubism is autosomal dominantly linked. Cherubism has also been found from the random mutation of a gene in an individual having no family history of the condition. However it is not well understood why males tend to express the disease more frequently. Children with cherubism vary in severity in their maxilla and mandible bony lesions. The disease is expressed at a rate of 80 to 100% of all affected. Studies of multiple generations of families with the gene found that all boys developed cherubism, but 30–50% of girls show no symptoms. The cause of cherubism is believed to be from a mutation of gene of SH3BP2. Cherubism has also been found combined with other genetic disorders including Noonan syndrome, Ramon syndrome, and fragile X syndrome. Mutations of the SH3BP2 gene are only reported in 75% of Cherubism cases.

Cherubism was first documented and named in 1933 by Dr. W. A. Jones of Kingston, Ontario, describing a case of three siblings of the same family of Jewish Russian heritage. All that was known at the time was the characteristic swelling pattern and the increase and then regress of bone lesions. By the time the children reached the ages of fifteen, sixteen, and seventeen, the facial deformity had become an obvious disfigurement and in 1943, the children were operated on by the Jones medical team, reducing the hard swelling of their jaws. Four years following the surgeries, there was no reappearance of the swellings. Yet, in some cases dysplasia recurred after surgery, necessitating additional surgeries.