Report of a patient with hypoglossia-hypodactylia syndrome and a review of the literature.

OBJECTIVE: To present the morphology of the extremities, craniofacial structures, and the oral cavity based on roentgencephalometry and three-dimensional computed tomography and magnetic resonance imaging scanning in a patient with hypoglossia-hypodactylia syndrome, discuss the orthodontic treatment method, and review the literature for the syndrome. PATIENT: The patient was a 6-year-old boy diagnosed with hypoglossia-hypodactylia syndrome at birth. He had hypodactylia as well as micrognathia with steep inclination of the anterior surface of the mandible in relation to the lower mandibular plane. He had missing mandibular incisors with concomitant bone defect limited to the associated alveolar ridge and an absence of any malformations in the mandibular ramus and condylar head. The patient had a bilateral scissors bite with an extremely constricted mandibular dental arch, skeletal Class II jaw relationship with an average mandibular plane angle and maxillary incisors inclined palatally. He had extremely reduced tongue size and hypertrophy of the floor of the mouth. Anomalies of the central nervous system were not observed. There was no evidence of hearing loss.