BILATERAL INFANTILE CATARACTOGENESIS IN A PATIENT WITH DEFICIENCY OF COMPLEX-I, A MITOCHONDRIAL ELECTRON-TRANSPORT CHAIN ENZYME

Progressive bilateral cataracts developed in infancy in a 5-month-old girl with deficiency of complex I, a mitochondrial electron transport chain enzyme. In the newborn period, she had severe lactic acidosis an d the diagnosis of complex I deficiency was confirmed by mitochondrial respiratory chain assay on muscle biopsy. By 5 months, she had comple tely opaque nuclear sclerotic cataracts, with loss of fixation and the red reflex. She underwent bilateral, sequential cataract extraction. The lens aspirate was submitted for cytologic analysis and electron mi croscopy, which revealed increased intracellular glycogen and swollen mitochondria. To our knowledge the association of complex I deficiency with cataracts in infancy has not been reported previously. The diagn osis of a respiratory chain enzyme defect in infancy is an indication for early ophthalmic evaluation to identify cataracts that may result in visual loss. Conversely the recognition of cataracts in infants wit h unexplained neurologic disease or metabolic acidosis may necessitate further evaluation for metabolic etiologies, including mitochondrial disorders.