Enlarged cerebral ventricular system in infant achondroplastic dwarf

The cause of the enlarged head found in achondroplastic dwarfs has been disputed. We studied an infant achondroplastic dwarf who had an enlarged (90%) head at age 2 months without enlarged cerebral ventricles. At age 10 months, her head size further enlarged (95%) and the cerebral ventricles were dilated. Megalencephaly may be the major factor contributing to the enlarged head in newborn achondroplastic dwarfs. Later, enlarged cerebral ventricles also contribute.