SLCO1B1*45 is assigned no function based on moderate evidence. SLCO1B1*45 is defined by c.1738C>T (p.R580X). This variant generates a premature stop codon resulting in the expression of a truncated protein. SLCO1B1*45 was significantly associated with increased bilirubin levels and an individual carrying SLCO1B1*45 experienced statin-associated muscle symptoms (38674010). Additionally, SLCO1B1 loss-of-function has been implicated in the pathogenesis of Rotor syndrome and SLCO1B1*45 has been identified in a homozygous state in probands (32082363, 36964102, 39071607, 25546334). Cryo-EM structural studies of SLCO1B1 protein have consistently identified p.R580 as a critical amino acid involved in substrate recognition and binding (40199401, 37674011). The SLCO1B1 protein contains 12 transmembrane domains; a truncation at p.R580 eliminates the final two transmembrane domains which is highly disruptive rendering the protein non-functional, as the full transmembrane architecture is required for substrate transport. Four out of four VEPs capable of making predictions for nonsense variants predict that c.1738C>T impairs protein function.