Of the 20 cases studied, thirteen rare variants were detected in nine genes: four in JAG1 (Alagille syndrome), two in MYO5B (progressive familial intrahepatic cholestasis [PFIC] type 6), and one each in ABCB11 (PFIC type 2), ABCC2 (Dubin-Johnson syndrome), ERCC4 (Fanconi anemia), KCNH1 (Zimmermann-Laband syndrome), MLL2 (Kabuki syndrome), RFX6 (Mitchell-Riley syndrome), and UG1A1 (Crigler-Najjar syndrome). The gene discussed is ERCC4; the disease is Crigler-Najjar syndrome.