Deficiency of the SCYL1 protein causes a rare autosomal recessive syndromal disorder characterized by low to mildly elevated gamma-glutamyltransferase (GGT) cholestasis, recurrent episodes of acute liver failure and neurodegeneration (CALFAN) syndrome [see Online Mendelian Inheritance in Man (OMIM) #616719] (Lenz et al., 2018; McNiven et al., 2021). The gene discussed is SCYL1; the disease is acute liver failure.