ANALYSIS OF COENZYME Q10 IN HUMAN TISSUES
Ubiquinone or Coenzyme Q10 (CoQ10) is an important component of the electron transport chain in the mitochondria (Figure 1). During oxidative phosphorylation, CoQ10 transfers electrons from complex I (NADH-CoQ reductase) and complex II (succinate dehydrogenase-CoQ reductase) to complex III (CoQ-cytochrome c reductase). In addition, there is good evidence that CoQ10 is a powerful antioxidant. We and others have identified patients with what appears to be primary CoQ10 deficiency in muscle and, presumably, in other tissues, including brain.
Primary CoQ10 deficiency has five main clinical presentations. (1), a "predominantly myopathic" form is characterized by the triad of: (i) exercise intolerance and recurrent myoglobinuria; (ii) mitochondrial myopathy with ragged-red fibers and lipid storage; (iii) central nervous system signs, including seizures, ataxia, or mental retardation. (2), An "ataxic" form characterized by cerebellar ataxia and cerebellar atrophy, with or without weakness, pyramidal signs, or peripheral neuropathy. (3), A severe "infantile form" characterized by encephalomyopathy and renal involvement. (4), "Leigh syndrome" with growth retardation, ataxia, and deafness. (5), A "pure myopathic" form. Importantly, all patients have shown clinical improvement after CoQ10 supplementation.
The best way to diagnose patients is through measurement of CoQ10 in muscle biopsies, where levels in patients have been consistently low (10%-25% of the normal mean). We have found lower than normal CoQ10 levels in cultured fibroblasts from patients with the ataxic and infantile forms. Measurements of CoQ10 in blood are important to follow patients on therapy, but they are not reliable for detecting CoQ10 deficiency.
Coenzyme Q10 from human tissue (blood or muscle) is extracted in an organic solvent, separated on a reversed-phase column, and measured by an electrochemical detection technique.
Draw one 7.0-mL purple-top tube (EDTA) of whole blood and invert several times to mix. The sample must be processed within 4 h of collection, it is preferable to keep it on ice but can be refrigerated if necesary. Centrifuge blood tubes at 2000 X g for 10 min at 4° C. Collect plasma in a capped polypropylene tube and store at -80 °C prior to shipping.
Muscle biopsies from any site on the patient are acceptable. The most common sites are thigh or arm. A minimum amount of 50 mg tissue is required, however 100 mg is preferred. Specimens must be frozen immediately and stored in liquid nitrogen or (-80°C or below deep freezer) prior to shipping.
Ship specimens via an overnight courier in a styrofoam container with 5 to 10 lbs of dry ice. Shipping time in excess of 24 hrs will result in failure to maintain appropriate temperatures and affects the results of the assay.
The plasma or muscle should be sent frozen, on dry ice, by overnight carrier to:
Dr. Ali Naini
Laboratory of Melocular Neurogenetics
Columbia University Medical Center
Department of Pathology
630 West 168th Street, P&S 17th Floor, Room 401
New York, NY 10032
82491 and 83912