Atlantoaxial malformation in a 46,XY, 17q+ child.

A child with 46,XY, 17q+ chromosome aberration and unusual skeletal abnormalities had the presenting symptom of respiratory arrest after a fall and minor head trauma. He exhibited proportionate short stature, peculiar facies with antimongoloid slant, simian creases, postaxial hexadactyly, metatarsus adductus deformity, and anomalous penoscrotal configuration. Delayed speech and mild mental retardation were also present. Atlantoaxial dislocation secondary to odontoid process hypoplasia was demonstrated. Additional skeletal abnormalities included dysplastic changes in the first and fourth metacarpals, the middle phalanx of the second finger, and hypoplasia of the first metatarsal, with medial insertion of the great toe. Treatment consisted of halo jacket cast and fusion of the occiput to C1, C2, and C3. Early detection and preventive surgery for atlantoaxial dislocation is necessary to prevent neurological deficit and possibly death by respiratory failure.