In a case-control study using a clinically well-defined group of 41 multiple system atrophy (MSA) patients and 93 control subjects, the interleukin (IL)-8 (-251) TT genotype was associated with an approximately fourfold increased risk for MSA and, furthermore, this risk increased elevenfold with the simultaneous presence of the intercellular adhesion molecule-1 (ICAM-1: E469K) KK genotype, suggesting a gene-gene interaction. These data support a role for inflammation-related genes in risk for MSA.