Reduced bile flow - cholestasis - is usually the result of liver injury but is also seen in some inherited syndromes. In arthrogryposis-renal dysfunction-cholestasis syndrome (ARC), which is caused by mutations in the vacuolar sorting protein VPS33B, improper bile duct development in the liver contributes to the cholestasis part of the syndrome. Now, Matthews and co-workers describe a zebrafish model of ARC. They report that vps33b-deficient zebrafish larvae have poorly developed bile ducts and impaired lipid absorption, as do people with ARC, but that they lack the characteristic motor axon or renal defects (see p. ). In addition,they identify vps33b as a downstream target gene of the transcription factor hnf6, which regulates bile duct development in zebrafish. Further elucidation of the role of VPS33B in biliary development will require the identification of the proteins whose intracellular trafficking is disrupted by its loss.
