We report on 4 children from 2 unrelated families who appear to have the lethal ARC syndrome (arthrogryposis, renal tubular dysfunction, and cholestasis) together with the additional findings of nephrogenic diabetes insipidus and cerebral anomalies, including deafness. With increased survival time in our patients, paucity of the intrahepatic bile ductules and cholestasis progressed to cirrhosis, growth was severely impaired, and severe mental retardation became apparent. No evidence was found for peroxisomal, chromosomal, or mitochondrial disorders. We propose to amend the ARC mnemonic to ARCC-NDI (A-Arthrogryposis, R-renal Fanconi, C-cerebral, C-cholestasis, NDI-nephrogenic diabetes insipidus) to name the major manifestations of this syndrome, several of which have not been appreciated.