Subjects with markedly poor ICG clearance but without severe liver disease are diagnosed with constitutional ICG excretory defect (Namihisa et al., 1981; Anzai et al., 2020) and lack of OATP1B3 expression has been confirmed in these subjects by immunohistochemistry (Kagawa et al., 2017; Masuoka et al., 2020). Here, SLCO1B3 is linked to liver disorder.