Familial odontoid hypoplasia.

Odontoid hypoplasia is a developmental abnormality, which is often asymptomatic. However significant sequelae can occur in some individuals, particularly after head or neck trauma. This anomaly is not generally known to be familial. We report on four affected individuals in the same family with odontoid hypoplasia, suggesting autosomal dominant inheritance. This is an important observation in that evaluation of family members is warranted in order to identify those at risk of neurologic compromise.