Comprehensive Orthodontic Treatment of a Patient With Prader-Willi Syndrome.

Prader-Willi syndrome (PWS) is a rare genetic disorder caused by a defect in paternally expressed genes in the 15q11-q13 region. Prader-Willi syndrome affects many parts of the body and involves craniofacial and dentofacial abnormalities. We herein report the successful 2-stage orthodontic treatment of an 8-year-old girl with PWS caused by paternal 15q11-q13 deletion. She presented with a skeletal class II relationship with mandibular deviation, a deep overbite, and severe crowding of the lower dental arch. Functional appliance therapy was utilized to improve her skeletal discrepancy. The second phase of orthodontic treatment using fixed appliances was started at 14.5 years old, which improved her remained crowding and large overbite. As a result, her facial appearance and occlusion were improved without any discernible relapse after 2 years of retention. We describe the outcomes of orthodontic treatment for a patient with PWS and discuss the specific attention during orthodontic treatment.