UBC Theses and Dissertations
Studies of Erythrocyte Membrane Alterations in Duchenne Muscular Dystrophy Bridges, Michael Anthony
Duchenne Muscular Dystrophy (DMD) appears to be a generalized plasma membrane disorder involving many body tissues of affected individuals, including erythrocytes. Investigation of the myopathic aspects of this disease has suffered from difficulties in distinguishing between the immediate effects of the primary lesion in muscle and the sequelae of muscle fiber necrosis. However, since there are indications that erythrocytes may also be abnormal in DMD, it may be possible to characterize this primary lesion in these cells. Furthermore, examination of erythrocytes of DMD patients and their female "carrier" relatives may reveal convenient biochemical markers of the disease which may aid both in early patient diagnosis and in carrier detection. The present investigations comprise a screening study in which a variety of chemical and biochemical techniques were employed in order to compare the structural and functional characteristics of DMD patient and carrier erythrocytes with those of normal control erythrocytes. A number of red cell abnormalities were found to be present in erythrocytes from patients with DMD or from their female carrier relatives: alterations in erythrocyte membrane phospholipid contents, in membrane-bound enzymatic activities associated with active sodium and potassium transport, as well as in those believed to be related to active calcium extrusion, and in the osmotic fragility characteristics of intact red cells. Although these findings are still tentative, they provide evidence supporting the generalized membrane defect hypothesis of DMD, as well as suggest promising avenues for further investigation of the molecular basis of DMD pathogenesis utilizing red cells. Recognized mechanisms of cellular injury are discussed in the attempt to reconcile the experimental findings of these studies with those of other investigators, and parallels are drawn between the alterations observed in DMD erythrocytes and those exhibited by erythrocytes in various other disorders and in experimental models.
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