Congenital fiber type disproportion myopathy is described in two brothers with oculo-cerebro-renal syndrome of Lowe from the Department of Pediatrics, Tsuchiura Kyoudou Hospital; Ibaraki; Tsukuba University; Tokyo Medical and Dental University; and National Institute of Neuroscience; Kodaira, Japan. Both brothers had congenital cataracts, they were floppy as infants and psychomotor development was delayed. Both suffered febrile tonic seizures and one was hyperkinetic and had stereotypic hand movements. There was generalized muscle hypotonia, deep tendon reflexes were absent and serum creatine kinase activity was elevated. There was nystagmus in all directions of gaze. Biopsies of the biceps and brachia muscles showed selective type I fiber atrophy and mild type I fiber predominance similar to that observed in congenital fiber type disproportion myopathy. 
COMMENT. Selective type I muscle atrophy is uncommon and occurs in congenital nonprogressive myopathies, including nemaline myopathy, myotubular myopathy, central cord disease, and congenital fiber type disproportion. In association with type I fiber predominance it is observed in Pompe disease, Krabbe leukodystrophy and multiple sulfatase deficiency in which peripheral nerves are involved. The oculo-cerebro-renal syndrome of Lowe is characterized by mental retardation, glaucoma, congenital cataracts, and renal impairment. The elevated CPK led to the muscle biopsies in the present patients.