RESUMO
A tendency to bleed during scoliosis surgery has been reported repeatedly in Duchenne muscular dystrophy (DMD) and diagnostic studies show a prolonged bleeding time. The pathophysiological background is still not fully understood. The short dystrophin isoform dp71 is expressed in platelets and mediates contractile properties. We performed a bicentric, non-blinded, prospective diagnostic study in 53 patients with confirmed DMD. Extensive laboratory analyses included platelet aggregometry and platelet flow cytometry, as well as routine coagulation analyses. Results of laboratory diagnostics were correlated with clinical data. Patients were subgrouped and analyzed according to ambulatory status and cardiac involvement. Platelet aggregation was reduced after stimulation with ADP (adenosine triphosphate) [60%; reference range 66-84%]. In addition, in the DMD cohort the expression of platelet activation markers CD62 and CD63 (flow cytometry analyses) was significantly lower than in healthy controls, most prominent in non-ambulatory patients with cardiac involvement. There was no clear association with the location of the underlying mutations in the dystrophin gene. No further abnormalities were identified regarding primary or secondary hemostasis. This study shows that platelets of patients with DMD have decreased expression of CD62 and CD63 which are markers for platelet granule release. This may indicate that patients with DMD have an impaired platelet granule secretion which may explain to some extent the increased bleeding, especially in mucocutaneous areas and perioperatively.