The carbohydrate-deficient glycoprotein (CDG) syndromes are a group of genetic multisystem disorders with invariable involvement of the nervous system including severe olivopontocerebellar atrophy. We report two sets of sibs in whom the diagnosis of CDG syndrome type 1 was recognized at an older age because of marked olivopontocerebellar atrophy seen on MRI. Previous CT findings were interpreted as showing Dandy-Walker malformation. Three of the patients are also among the oldest reported with this syndrome.