Epidemiological evidence on multiple system atrophy.

Multiple system atrophy (MSA), is a sporadic neurodegenerative disorder characterized clinically by any combination of parkinsonian, autonomic, cerebellar or pyramidal symptoms and signs. The frequence of disease is estimated for the incidence rate to 0.6 cases per 100.000 person-years, while the prevalence rate is included between 1.86 and 4.9 cases per 100.000 pop. A risk factor seems to be the occupational history of farming also if the occupational exposure to pesticides is not associated with MSA. Smoking is probably a protective factor in MSA as Parkinson's disease. MSA seems a sporadic disease also if recently a German family with two MSA cases has been reported. The polymorphism association studies support a role for inflammation-related genes in risk for MSA. The current epidemiological and clinical evidence suggests that likely the etiopathogenesis of MSA is complex, and that many genetic as well as environmental factors are involved. Unfortunately, the most of studies in MSA are lacking in a sample size estimate to test the hypothesis, then the scientific evidence is poor. Then, much larger numbers of cases and controls are necessary for these studies to reach sufficient power, but collecting such large numbers is feasible only in the framework of multicentric consortia.