A single nucleotide polymorphism (SNP) in the TRAILR-1 gene is associated with the clinical response to IFN-β therapy in patients with multiple sclerosis (MS), according to a study conducted in a Spanish cohort. TRAILR-1 encodes a receptor for TRAIL, a proapoptotic cytokine that has been implicated in MS pathogenesis. The CC genotype of the rs20576 SNP, which results in a Glu228Ala substitution in TRAILR-1, was found to correlate with an enhanced response to IFN-β, and might be a useful biomarker to predict the outcome of this treatment.