SLCO1B1*20 is assigned increased function based on limited in vitro evidence and limited clinical data. Small clinical studies of pravastatin and atorvastatin showed similar pharmacokinetic parameters to subjects with wildtype alleles (15226675, 23311897). One clinical study found significantly increased methotrexate clearance (22147369). The plasma levels of highly sensitive OATP1B1 endogenous substrate GCDCA-3G are significantly lower in *14 carriers than in individuals with the SLCO1B1*1/*1 diplotype (32961594). Therefore, consensus among experts was increased function due to inadequate evidence.