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Objective Based on targeted next generation deep sequencing,we aimed to sketch the gene mutation footprint of hepatocellular carcinoma(HCC)unique to Han races,to uncover potential druggable target gene mutation and to calculate tumor mutation burden(TMB)and then to explore the relationship between tumor mutation burden and hepatocellular carcinoma patients clinical characteristics.Methods We performed next-generation deep sequencing on paired tumor tissues and paratumor tissues of 106 HCC patients who previously underwent hepatic resection or liver transplantation operation in department of liver surgery and transplantation,liver cancer institute,Zhongshan hospital,Fudan university by using commercial Oseq-T 508 gene panel.The Research Ethics Committee of Zhongshan Hospital approved the ethical use of human subjects for this study,and informed consent was obtained from each patient.Captured DNA fragments were sequenced on BGISEQ-500 as paired-end 100-base pair reads.Raw data were filtered by SOAPnuke-1.2.0 to eliminate low quality reads and adapter contamination.After which the remaining high quality reads were mapped to the human genome(hg19)using BWA aligner v0.6.2 and Samtools v0.1.19.Picard v1.98 was used to mark PCR duplications and GATK v2.3-9 was utilized to execute alignment refinement.SAMtools were used to filter non-primary alignment sequence.MuTect and Som_snp were used separately to generate somatic SNVs based on paired tumor and normal samples and the results were combined together as the initial somatic SNVs.Similarly,INDELs were called by both GATK and SOMATIC_indel softwares.And CNV or fusion mutation were analyzed by som_sv.Mapping quality,base quality and mutation frequency were used to filter real somatic mutations with high confidence coefficient evaluated by different hypothesis testing.Tumor mutation burden value was calculated by using MSK-IMPACT method.SPSS 23.0(IBM)software was used for statistical analysis and P < 0.05 was deemed to be significant.Results Totally,we detected 769 somatic mutations in 106 HCC patients,which includes 529 missense mutations(68.88%),90 nonsense mutations(11.72%),59 frameshift muations(7.68%),17 splicing mutations(2.21%),24 copy number gain variations(3.13%),3 copy number loss variations(0.39%),17 in-frame shift mutations(2.21%),4 germline mutations(0.52%).Among above detected variations,47 of them have targeted druggable potential.Amid 312 genes which had variations,the number of gene whose mutation frequency was 1,2 and >3 were 152(48.72%),69(22.12%)and 91(29.16%),respectively.The mean TMB value was 11.14/Mb(0.59/Mb-35.88/Mb)based on sequencing data from 91 HCC patients who were accessible for TMB analysis.TMB value was higher in patients with advanced BCLC stage(P < 0.05)and individuals with micro vessel invasion had a higher TMB value(P = 0.048),while no significant correlation was found between TMB value and patients with or without macro vein invasion.Moreover,TMB value was significantly elevated in patients with hepatitis G score grade 1-3 than those with G score grade 0(P < 0.05).Furthermore,subjects who had liver fibrosis had a significantly higher TMB value than those without liver fibrosis(P = 0.035).Conclusions Next-generation sequencing gene panel is of promising prospect to detect potential druggable target mutation in hepatocellular carcinoma patients.TMB based on sequencing data can to some extent reflect aggressive behaviors of HCC.