Treatment with 4-PB of six patients with PFIC2 carrying the G982R, R1128C, T1210P, R1231Q, and the Y157C/G1298R variations of ABCB11 and of one BRIC2 patient carrying the D404G variation resulted in a decrease in cholestasis [9,11,14,15,16]. The gene discussed is ABCB11; the disease is cholestasis.