In a case-control study using a clinically well-defined group of 30 multiple system atrophy (MSA) patients and 110 control subjects, homozygosity for interleukin-1A (IL-1A) allele 2 (high secretor of proinflammatory cytokine) in the regulatory region (-889) of the IL-1A gene was associated with a fivefold increased risk for MSA.