An Adult Case of Benign Recurrent Intrahepatic Cholestasis Due to MYO5B Deficiency.

Abnormalities in MYO5B, which encodes an unconventional myosin Vb, not only cause microvillus inclusion disease but also cholestatic liver disease, including benign recurrent intrahepatic cholestasis (BRIC). However, MYO5B-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 MYO5B: a nonsense mutation (c. G1124A: p. W375X) and a missense mutation (c.C2470T: p.R824C). Therefore, the patient was diagnosed with MYO5B-associated BRIC. This is the first reported case of cholestasis with a defined MYO5B defect in Japan.