Ophthalmoplegic Neuromuscular Disorder With Abnormal Mitochondria

Among 6 offspring of first-cousin Japanese parents, Tamura et al. (1974) described 2 with external ophthalmoplegia with ptosis and involvement of cranial nerves and skeletal muscles. Muscle biopsies showed marked morphologic alterations of mitochondria. Only external ophthalmoplegia was found in 1 sib, and a fourth had died presumably of the full disorder. The disorder began with ptosis in the late teens. Okamoto et al. (1981) described the ophthalmoplegia-plus syndrome in brother and sister. Computerized tomography scan showed diffuse, low-density deep cerebral white material. Prednisone was effective in restoring strength in the limbs. The disorder described by Tamura et al. (1974) has similarities to the Kearns-Sayre syndrome (530000), appears to represent a mitochondrial cytopathy, and may be mitochondrially inherited. The parental consanguinity suggests, however, that a nuclear mutation and autosomal recessive inheritance are involved.