Hepatocellular carcinoma (HCC), a leading cause of cancer-related mortality worldwide, is driven by complex interactions between genetic mutations and reversible epigenetic alterations. Among these, aberrant DNA methylation, histone modifications, and dysregulated noncoding RNAs (ncRNAs) play central roles in hepatocarcinogenesis, tumor progression, and therapy resistance. Epigenetic changes not only regulate key oncogenic pathways, including JAK/STAT and RAS, but also contribute to tumor immune evasion and heterogeneity. Unlike genetic mutations, epigenetic alterations are reversible, offering unique opportunities for therapeutic targeting. This review highlights recent advances in understanding the epigenetic landscape of HCC, identifies promising biomarkers for early detection and prognosis, and evaluates emerging epigenetic therapies (including DNMT, HDAC, and BET inhibitors as well as ncRNA-based strategies). Although these therapies have shown tumor-suppressive or treatment-sensitizing effects in preclinical models, their clinical translation remains limited by modest efficacy, small early-phase trials, treatment-related adverse events, and insufficient biomarker-guided patient selection. These insights may support more precise diagnostic and therapeutic strategies for HCC.

Background: Progressive familial intrahepatic cholestasis (PFIC) describes a group of genetically heterogeneous disorders. Several mutations in the ATP-Binding Cassette Subfamily B Member 4 (ABCB4) gene have been confirmed to cause reduced phosphatidylcholine levels in bile, leading to a deficiency of biliary vesicles and instability of mixed in micelles. The disease spectrum ranges from PFIC type 3 (PFIC3) to milder conditions. Herein, we present a rare case of PFIC3 in a young woman, emphasizing the importance of early detection and management. Methods: The patient was diagnosed using next-generation sequencing, with genetic testing and analysis performed by the Chengdu Hua Chuang Testing Institute. Variant pathogenicity was evaluated according to the American College of Medical Genetics and Genomics guidelines and classified into five categories: pathogenic, likely pathogenic, uncertain significance, likely benign, and benign. Nomenclature was assigned following the Human Genome Variation Society standards. Results: Contrast-enhanced abdominal computed tomography demonstrated liver cirrhosis with marked splenomegaly. Histological examination of liver biopsy specimens using hematoxylin and eosin and Masson staining further confirmed cirrhotic changes. Genetic testing was subsequently performed and revealed a likely pathogenic variant, c.2757T > A (p. Tyr919Ter), in exon 22 of the ABCB4 gene, which was also detected in the patient’s mother but absent in her father. Finally, PFIC3 was diagnosed. Following initiation of ursodeoxycholic acid therapy, the patient showed moderate improvement in liver function tests, underscoring a clinical case with therapeutic implications. Conclusions: Molecular genetic analyses of ABCB4 are essential for the accurate diagnosis of PFIC3. Clinicians should consider cholestatic liver diseases, particularly PFIC, as a differential diagnosis in cases of liver cirrhosis with unknown etiology, especially in young patients who lack prior symptoms or a family history of liver disease.