Mutations in BCS1L, encoding an assembly factor of cIII, have been associated with different clinical phenotypes such as GRACILE (acronyn for Growth Retardation, Aminoaciduria, Cholestasis, Iron overload, Lactic acidosis and Early death) syndrome, Bjornstad syndrome, neonatal proximal tubulopathy, hepatopathy and encephalopathy. The gene discussed is BCS1L; the disease is Björnstad syndrome.