The SLCO1B1*5 allele (defined as consisting of rs4149056) is assigned as a no function allele by CPIC. Patients carrying SLCO1B1*5 allele in combination with a normal, no, or increased function allele may have a higher risk of atorvastatin-related myopathy when treated with atorvastatin as compared to patients with two normal function alleles. However, conflicting evidence has been reported. Other genetic and clinical factors may also influence the toxicity of atorvastatin.