Objective: To investigate the clinical and genetic characteristics and predictive role of the severe liver disease phenotype in patients with hepatolenticular degeneration (HLD). Methods: Inpatients with HLD confirmed at Xinhua Hospital affiliated with Shanghai Jiao Tong University School of Medicine from January 1989 to December 2022 were selected as the research subjects. Clinical classification was performed according to the affected organs. Patients with liver disease phenotypes were classified into the liver disease group and further divided into the severe liver disease group and the ordinary liver disease group. The clinical characteristics and genetic variations were compared in each group of patients. The predictive indicators of patients with severe liver disease were analyzed by multiple regression. Statistical analysis was performed using the t-test, Mann-Whitney U test, or χ(2) test according to different data. Results: Of the 159 HLD cases, 142 were in the liver disease group (34 in the severe liver disease group and 108 in the ordinary liver disease group), and 17 were in the encephalopathy group. The median age of onset was statistically significantly different between the liver disease group and the encephalopathy group [12.6 (7.0, 13.3) years versus 16.9 (11.0, 21.5) years, P<0.01]. 156 ATP7B gene mutation sites were found in 83 cases with genetic testing results, of which 54 cases carried the p.Arg778Leu gene mutation (allele frequency 46.2%). Compared with patients with other types of gene mutations (n=65), patients with homozygous p.Arg778Leu mutations (n=18) had lower blood ceruloplasmin and albumin levels, a higher prognostic index, Child-Pugh score, an international normalized ratio, and prothrombin time (P<0.05). Hemolytic anemia, corneal K-F ring, homozygous p.Arg778Leu mutation, and multiple laboratory indexes in the severe liver disease group were statistically significantly different from those in the ordinary liver disease group (P<0.05). Multivariate logistic regression analysis showed that the predictive factors for severe liver disease were homozygous p.Arg778Leu mutation, total bilirubin, and bile acids (ORs=16.512, 1.022, 1.021, 95% CI: 1.204-226.425, 1.005-1.039, and 1.006-1.037, respectively, P<0.05). The drawn ROC curve demonstrated a cutoff value of 0.215 3, an AUC of 0.953 2, and sensitivity and specificity of 90.91% and 92.42%, respectively. Conclusion: Liver disease phenotypes are common in HLD patients and have an early onset. Total bilirubin, bile acids, and the homozygous p.Arg778Leu mutation of ATP7B is related to the severity of liver disease in HLD patients, which aids in predicting the occurrence and risk of severe liver disease.