Mitochondrial complex I deficiency is the most common defect of the oxidative phosphorylation system. It is clinically heterogeneous, leading to a broad variety of clinical manifestations ranging from neonatal death to late-onset neurodegenerative disorders. We report a patient with Leigh syndrome who showed a complex I deficiency in cultured fibroblasts.

Keywords: <i>kompleks I eksikliği, laktik asidoz, mitokondrial hastalık.</i>