Free radicals, lipid peroxides and antioxidants in blood of patients with myotonic dystrophy.

We studied the levels of free radicals, lipid peroxides and antioxidants, as well as superoxide dismutase (SOD) activity in the blood of six patients with myotonic dystrophy (MyD) (mean age 52.8, SD 5.0 years) and seven controls (mean age 48.8, SD 6.3 years). Electron spin resonance was used to assess the free radicals by the spin-trapping method using 5,5-dimethyl-1-pyrroline-1-oxide. The levels of C centre radical (P < 0.05) and H radical (P < 0.05) in blood from the six MyD patients were significantly higher than those in the seven controls. The SOD activities in red blood cells and serum from the six MyD patients showed no significant difference from those in the seven controls. The serum lipid peroxide concentration was increased in five of the MyD patients and tended to increase further as the disease progressed. The serum vitamin E level was low in two patients and in the low normal range in three. Serum coenzyme Q10 was decreased in four patients. The serum selenium level was decreased in two patients and that of serum albumin was decreased in three. Therefore we conclude that increased levels of free radicals and lipid peroxides and decreased antioxidant levels play an important role in the pathogenesis of MyD.