Granulocyte dysfunction and myotonic dystrophy

A 52-year-old Caucasian male with typical features of myotonic dystrophy (MD) developed a lung abscess and was found to have a mild atypical cyclic neutropenia. Granulocyte function testing revealed a defect in phagocytosis, bactericidal activity and chemotaxis. The defects were less severe at the nadir of the granulocyte counts. Skin windows demonstrated that the granulocyte defects were not just an in vitro artifact. The patient was treated with lithium carbonate and improved. Mobilization into a skin window and clinical MD were unchanged. Studies of his 10 children and 2 siblings, including granulocyte function tests and complete neurological evaluations were obtained. The 4 children with abnormal parameters of granulocyte function all had definite evidence of MD. Two children had equivocal findings of MD and the others were normal. There was minimal evidence of granulocyte dysfunction in these children. Twelve of 19 unrelated patients with MD had evidence of impaired granulocyte function with the most consistent defect being chemotaxis in response to bacterial factor. Mild granulocyte dysfunction is frequently associated with MD, but severe dysfunction with many defects is uncommon but can occur, as in this family. There was a tendency for the more severely afflicted members of this family to have more pronounced granulocyte dysfunction. Longitudinal testing in this family may determine any relationship between the granulocyte dysfunction and the onset of MD, as well as any correlation with the progression of the disorder. MD patients who develop infection should have granulocyte function tests as part of their evaluation.