Increased levels of tPA antigen and tPA/PAI-1 complex in myotonic dystrophy

Objective. To assess the fibrinolytic system in myotonic dystrophy (DM1), a disease connected to features of the metabolic syndrome, including a promi nent insulin resistance, increased body fat mass, and hypertriglyceridaemia . We hypothesized that abnormalities in the fibrinolytic system are linked to metabolic dysfunction in DM1. Design. Circulating morning levels of tissue plasminogen activator (tPA) an d plasminogen activator inhibitor type 1 (PAI-1) antigens, tPA/PAI-1 comple x, lipids and insulin were determined. Genetic analyses, including calculat ion of allele size, were performed in all patients. Body fat mass was estim ated with bioelectrical impedance analysis. Setting. Out-patient clinic in collaboration with Umea University Hospital. Subjects. A total of 42 otherwise healthy patients with DM1 (22 men, 20 wom en; median age 41.5 years) and 50 controls (27 men, 23 women; median age 42 .0 years), Main outcome measures. The tPA and PAI-1 antigens, tPA/PAI-1 complex, blood lipids and body fat mass. Results. The tPA antigen and tPA/PAI-1 complex levels were significantly in creased in DM1 patients (P < 0.001 and P < 0.05, respectively) whilst level s of PAI-1 did not differ from controls. Triglyceride levels were increased (P < 0.001) whereas HDL cholesterol levels were lower in DM1 patients (P < 0.05). Body fat mass was increased in DM1 patients (P < 0.001). Conclusions. The fibrinolytic system is disturbed in DM1 patients; with inc reased levels of tPA and tPA/PAI-1 complex but paradoxically unaltered leve ls of PAI-1, in spite of a severely increased body fat mass. This may imply an abnormal function of adipose tissue in DM1, and calls for further studi es of the fibrinolytic system in this disease.