Myhre syndrome: a rare craniofacial disorder.

AIMS: Myhre syndrome is a rare disorder characterized by abnormal growth of the skeleton, muscles, and joints. The relationship of this syndrome to craniofacial growth and development is unknown. To the authors' knowledge, this is the first Japanese case ever studied.

METHODOLOGY: At 10 years and 7 months of age, the patient was referred to the Department of Pediatric Dentistry in the authors' hospital, complaining of a dental problem.

RESULTS: The craniofacial region exhibited a long lower face, high and narrowed palate with submucous cleft palate, maxillary constriction, prognathism, open bite, and crowding of the dental arch. Some of these morphological disorders could be affected by the functional manifestations of muscular hypertrophy of the cheek region, muscle tenseness, or the low position of the tongue. General disorders of muscular hypertrophy, thickened bones, and limited joint mobility are consistent with craniofacial findings of muscle tension in the cheek region, thickened calvarium, and limitation of temporomandibular joint movement. The submucous cleft palate and crown deformation of the mandibular central incisor may be affected by dysfunctions of SMAD4 signaling.

CONCLUSIONS: Craniofacial growth and development is affected by the general characteristics of Myhre syndrome, and could be important in its diagnosis.