Patients carrying the CYP2D6*2xN allele in combination with a normal function allele may have increased methadone dose requirements as compared to patients carrying two normal function alleles. However, conflicting evidence has been reported. This drug-variant pair has been assigned a 鈥渘o recommendation鈥?by CPIC, as it was determined to be not clinically actionable. Other genetic and clinical factors may also affect methadone dose requirements.