The CYP2C19*1 allele is assigned as a normal function allele by CPIC. Patients carrying the CYP2C19*1 allele in combination with a normal function allele who are treated with citalopram may have decreased, but not absent, risk for treatment related side effects or intolerance as compared to patients with two no function alleles or a normal function allele in combination with a no function allele. However, conflicting evidence has been reported. Other genetic and clinical factors may also influence treatment related side effects.