ATOX1, COMMD1, and XIAP were shown not to contribute significantly to the WD phenotype (Kieffer and Medici 2017), whereas polymorphisms in PNPLA3, a lipase involved in hepatocyte triglyceride metabolism, were associated with increased hepatic steatosis in WD (Stättermayer et al., 2015). This evidence concerns the gene PNPLA3 and Wilson disease.