These two types, along with Gilbert's syndrome, Dubin–Johnson syndrome, and Rotor syndrome, make up the five known hereditary defects in bilirubin metabolism.
Ova dva tipa, zajedno sa Gilbertovim sindromom, Dubin—Džonsonovim sindromom i Rotorovim sindromom, su pet poznatih naslednih defekata u biliribinskom metabolizmu.