SLCO1B1*39 is assigned no function based on limited evidence. SLCO1B1*39 is defined by c.388A>G (p.N130D, defining *37) and c.757C>T (p.R253X). The latter results in the generation of a premature stop codon and expression of a truncated protein while c.388A>G is associated with normal SLCO1B1 function. The nonsense variant occurs upstream of the known "no function" variant (c.1463G>C, defining *9 and *31), suggesting that loss of this region of the protein alters function. Additionally, SLCO1B1 loss-of-function has been implicated in the pathogenesis of Rotor syndrome and SLCO1B1*39 has been identified in a homozygous or compound heterozygous state in three cases (32082363, 36964102). Ten out of ten variant effect predictors (VEPs) tested by CPIC staff predict that c.388A>G is neutral for protein function. Four out of four VEPs capable of making predictions for nonsense variants predict that c.757C>T impairs protein function.