Affiliations: Clinical Chemistry and Neurology Departments, Hospital
Sant Joan de Déu, Barcelona, Spain | Institut de Bioquímica Clínica-CSIC,
Barcelona, Spain | Universidad Pablo de Olavide, Sevilla, Spain | Departamento de Bioquímica y Biología
Molecular, Universidad de Zaragoza, Spain
Note: [] Address for correspondence: Rafael Artuch, Clinical Chemistry
Department, Hospital Sant Joan de Déu, Passeig Sant Joan de Déu,
2, 08950 Esplugues, Barcelona, Spain. Tel.: +34 932806169; Fax: +34 932803626;
E-mail: rartuch@hsjdbcn.org
Abstract: Coenzyme Q_{10} (CoQ) deficiency syndrome is a
disorder of unknown ethiology that may cause different forms of mitochondrial
encephalomyopathy. In the present study our aim was to analyse CoQ
concentration and mitochondrial respiratory chain (MRC) enzyme activities in
muscle biopsies of patients with clinical suspicion and/or
biochemical-molecular diagnosis of a mitochondrial disorder. We studied 36
patients classified into 3 groups: 1) 14 patients without a definitive
diagnosis of mitochondrial disease, 2) 13 patients with decreased CI+III
and II+III activities of the MRC, and 3) 9 patients with definitive
diagnosis of mitochondrial disease. Only 1 of the 14 patients of group 1 showed
slightly reduced CoQ values in muscle. Six of the 13 patients from group 2
showed partial CoQ deficiency in muscle and 1 of the 9 cases from group 3
presented a slight CoQ deficiency. Significantly positive correlation was
observed between CI+III and CII+III activities with CoQ
concentrations in the 36 muscle homogenates from patients (r=0.555; p=0.001;
and r=0.460; p=0.005, respectively). In conclusion, measurement of MRC enzyme
activities is a useful tool for the detection of CoQ deficiency, which should
be confirmed by CoQ quantification.
