An Adult Case of Benign Recurrent Intrahepatic Cholestasis Due to <i>MYO5B</i> Deficiency.

Abnormalities in <i>MYO5B</i>, which encodes an unconventional myosin Vb, not only cause microvillus inclusion disease but also cholestatic liver disease, including benign recurrent intrahepatic cholestasis (BRIC). However, <i>MYO5B</i>-related cholestasis has not yet been reported in Japan. In this study, we present the case of a female patient in her thirties, who had developed jaundice, without diarrhea, in the first year after birth. The jaundice spontaneously subsided and occasionally recurred. Whole-exome sequencing identified two pathogenic variants in <i>MYO5B</i>: a nonsense mutation (c. G1124A: p. W375X) and a missense mutation (c.C2470T: p.R824C). Therefore, the patient was diagnosed with <i>MYO5B</i>-associated BRIC. This is the first reported case of cholestasis with a defined <i>MYO5B</i> defect in Japan.