In the Serbian cohort, PAI-1 5G5G homozygosity (OR = 1.54, 95% CI 1.04–2.28, P = 0.032) was positively associated with MS, and 4G5G heterozygosity (OR = 0.68, 95% CI 0.50–0.92, P = 0.012) was negatively associated with MS compared to controls. This evidence concerns the gene SERPINE1 and myeloid sarcoma.