The CYP2D6*36 allele is assigned as a no function allele by CPIC. Patients carrying the *36 allele in combination with another no function allele, a normal function allele or a decreased function allele with an activity value of 0.25 may have lower clearance of flecainide as compared to patients carrying alleles that result in a normal metabolizer phenotype. Other genetic and clinical factors may also influence flecainide metabolism. This annotation only covers the pharmacokinetic relationship between CYP2D6 and flecainide and does not include evidence about clinical outcomes.