Identical Mutation in SH3BP2 Gene Causes Clinical Phenotypes with Different Severity in Mother and Daughter - Case...

Cherubism is a particular form of fibrous dysplasia of the jaws. Familial occurrence was reported in most cases. The condition is a rare hereditary disorder with autosomal dominant inheritance, with complete penetrance in males and incomplete penetrance in females and variable expressivity. It is known to be caused by mutations in the gene encoding SH3-domain binding protein 2, SH3BP2 gene. Major diagnostic criteria are cherubic facial appearance, painless hard enlargement of the jaws, and frequently associated dental abnormalities. The aim of the study was to analyze clinical and genetic features of cherubism in a family with 3 daughters in which the youngest one was affected. Clinical and radiographic examinations, hematological and biochemical evaluations and biopsy were performed. Molecular genetic analysis consisted of PCR amplification and direct sequencing of selected exons of the SH3BP2 gene. Cherubism was suspected based on clinical and radiographic examinations of the 9-year-old daughter. She presented asymmetrical enlargement of the mandible, speech and swallowing problems and dental abnormalities on the lower jaw. There was no history of similar clinical findings in any of the daughters or the parents of the affected girl. Abnormal results were obtained by genetic analysis. A c.1244G>A mutation was identified in exon 9 of the SH3BP2 gene in the asymptomatic mother and her affected daughter. The identified mutation in the SH3BP2 gene is probably disease-causing. The asymptomatic mother transmitted the gene mutation to her affected daughter. Our results confirm the reduced penetrance and variable expression of the gene mutation.