The SLCO1B1*15 allele (defined as consisting of both rs4149056 and rs2306283) is assigned as a no function allele by CPIC. Patients carrying SLCO1B1*15 allele in combination with a normal, no, or increased function allele may have a higher risk of pravastatin-related myopathy when treated with pravastatin 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 pravastatin.