Variation in MYO5B, encoding the motor protein myosin Vb (MYO5B), can cause microvillus inclusion disease and/or familial intrahepatic cholestasis (FIC) with normal/low serum gamma-glutamyltransferase (GGT<100 IU/L) activity [1–4]. The gene discussed is MYO5B; the disease is familial intrahepatic cholestasis.