To explore whether genetic changes in cancer-related genes can be identified in chronic hepatitis B patients with HCC, we performed targeted sequencing to detect the incidence of mutations in six selected cancer-related genes including ARID1A, TP53, FAT4, HNF4α, PIK3CA and IRF2. These genes have been suggested to play functional roles in chromatin remodeling (ARID1A), tumor suppression (TP53 and FAT4), transcription activation (HNF4α and IRF2), and oncogenic development (PIK3CA) (Additional file 1: Table S1) [18–20]. The gene discussed is PIK3CA; the disease is cancer.