Freeze-fracture analysis of cholesterol in muscle plasma membrane of Fukuyama-type congenital muscular dystrophy.

We used digitonin in freeze-fracture analysis of the muscle plasma membrane cholesterol content in six patients with Fukuyama-type congenital muscular dystrophy and six control children. A significantly greater proportion of surface area was taken up by digitonin-cholesterol complexes in the patients (51.2% +/- 4.7%) than in controls (31.9% +/- 2.9%) (P less than 0.01). Since membrane cholesterol has a dynamic regulatory function in affecting the activity of membrane-bound proteins, the increased cholesterol content in the patients suggests a functional abnormality of the muscle plasma membrane in this disease.