ZFYVE19 is a zinc finger FYVE-type protein that functions as a key regulator of cytokinesis, specifically controlling the abscission checkpoint that prevents premature cell division completion 1. The protein works with CHMP4C to retain VPS4 at the midbody ring, delaying abscission until checkpoint signaling terminates [UniProt Function]. Beyond cytokinesis, ZFYVE19 plays critical roles in cilia and centrosome biology, as its deficiency causes centriole and axoneme abnormalities 2. ZFYVE19 also supports intracellular Salmonella proliferation during infection 3. Biallelic loss-of-function ZFYVE19 variants cause progressive familial intrahepatic cholestasis type 9, a ciliopathy presenting with neonatal-onset high gamma-glutamyl transferase cholestasis 42. Patients develop ductal plate malformation, congenital hepatic fibrosis, and portal hypertension, with ciliary dysfunction and increased hepatocyte death contributing to disease pathogenesis 1. TGF-β and JAK-STAT3 signaling pathways are activated, promoting biliary fibrosis 1. Most patients remain liver-confined without systemic manifestations 5. Ursodeoxycholic acid provides temporary biochemical improvement but does not prevent cirrhosis progression 6. Liver transplantation shows excellent long-term outcomes, with all transplanted patients surviving and remaining asymptomatic 5.