J Neural Transm (2000) 107: 1021–1026 Serum levels of coenzyme Q 10 in patients with amyotrophic lateral sclerosis J. A. Molina 1 , F. de Bustos 2 , F. J. Jiménez-Jiménez 3 , C. Gómez-Escalonilla 1 , A. García-Redondo 2 , J. Esteban 1 , A. Guerrero-Sola 4 , P. del Hoyo 2 , A. Martínez-Salio 1 , C. Ramírez-Ramos 4 , G. Ruiz Indurain 1 , and J. Arenas 2 1 Department of Neurology and 2 Department of Biochemistry, Hospital Universitario Doce de Octubre, 3 Department of Medicine-Neurology, University of Alcalá, Alcalá de Henares, 4 Service of Neurology, Hospital Universitario San Carlos, Madrid, Spain Received September 1, 1999; accepted January 4, 2000 Summary. To elucidate whether serum coenzyme Q 10 levels are related with the risk for amyotrophic lateral sclerosis (ALS), we compared serum levels of coenzyme Q 10 and the coenzyme Q 10 /cholesterol ratio, in 30 patients with ALS and 42 matched controls using a high performance liquid chromatography technique. The mean serum coenzyme Q 10 levels and the coenzyme Q 10 / cholesterol ratio did not differ significantly between the 2 study groups. These values were not influenced by the clinical form (spinal vs. bulbar) of ALS, and they did not correlate with age, age at onset, and duration of the disease. These results suggest that serum coenzyme Q 10 concentrations are unrelated with the risk for ALS. Keywords: Amyotrophic lateral sclerosis, motoneuron disease, coenzyme Q 10 , serum levels. Introduction The etiology and pathogenesis of amyotrophic lateral sclerosis (ALS) is un- known. It has been suggested a role of genetic and environmental factors, autoimmune mechanisms, oxidativestress, excitotoxicity, viral infection, cytoskeletal abnormalities, and loss of trophic support (Coria and Cuadrado, 1996; Louvel et al., 1998). Rosen et al. (1993) described mutations in the Cu/Zn superoxide dismutase (SOD-1) gene in a subgroup of patients with familial ALS (FALS). Since then, there has been identified a number of mutations in the SOD gene which could explain around 20% of FALS (Coria and Cuadrado, 1996; Louvel et al., 1998). These findings suggested a possible role of oxidative stress in the pathogenesis of ALS (Coria and Cuadrado, 1996; Bergeron, 1995).