The CYP2C9*3 allele is assigned as a no function allele by CPIC. Patients carrying the CYP2C9*3 allele in combination with a normal, decreased or no function allele may have decreased metabolism and increased plasma concentrations of siponimod as compared to patients carrying two normal function alleles. Other genetic and clinical factors may also influence metabolism of siponimod. This annotation only covers the pharmacokinetic relationship between CYP2C9 and siponimod and does not include evidence about clinical outcomes.