Lymphocyte abnormality in human myotonic dystrophy and experimental drug-induced myotonia

In the cytoplasm of peripheral blood lymphocytes in 3 of 13 patients with myotonic dystrophy, myelin-like structures were observed electronmicroscopically. Some were connected to the cytoplasmic membranes, and some were surrounded by a limiting membrane possessing acid phosphatase activity. These findings suggest an aberration of cytoplasmic membranes in lymphocytes. Similar structures had appeared in lymphocytes of normal rats that became myotonic with 20, 25-diazacholesterol. These findings suggest that a primary genetic defect in human myotonic dystrophy, which participates in the formation of myelin-like structures in lymphocytes, might be also responsible for the occurrence of a myotonic phenomenon.