Mutational complex genotype of the hepatitis B virus X /precore regions as a novel predictive marker for hepatocellular carcinoma

Abstract

This study explored the combined effect of number and pattern of mutations in the X ⁄ precore regions of the hepatitis B virus (HBV) genome, mutational complex genotype (MCG), on hepatocellular carcinoma (HCC) development. Sequence variations were determined by direct sequencing and multiplex restriction fragment mass polymorphism analysis in 150 age-, sex-and hepatitis B e antigen (HBeAg) status-matched patients with and without HCC. In addition, a longitudinal study and an external validation of MCG were conducted. All were HBV subgenotype C2. Eight highfrequency mutations (G1613A, C1653T, T1753V, A1762T, G1764A, A1846T, G1896A and G1899A) were significantly associated with HCC. Whereas C1653T, T1753V, G1764A and A1846T were independent mutational factors for HCC, the significance of these individual mutations was negligible when analyzed with all clinico-virological variables. The total number of mutations was the only independent viral factor for HCC, irrespective of HBeAg status. There was a significant dose-risk relationship between the number of mutations and HCC, in which high risks for HCC were associated with mutation numbers ‡6. Pattern analysis of the mutations revealed disparity in distribution among the top seven high-risk mutation combination patterns, which accounted for 40 and 2.7% of HCC and non-HCC cases, respectively. The predictive accuracy of the high-risk mutations for HCC was similar to that of a-fetoprotein. Longitudinal and external validation studies also supported the association of mutation number with HCC development. MCG in the HBV X ⁄ precore regions is a risk indicator for HCC, and might serve as a new guide to the HCC screening scheme for chronic HBV carriers. (Cancer Sci 2012; 103: 296-304) H epatocellular carcinoma (HCC) is a major malignancy worldwide, ranking as the fifth most common cancer. Hepatitis B virus (HBV) infection is a major global cause of HCC, with chronic HBV carriers having a 100-fold increased risk for developing HCC compared to non-carriers.(1) Identification of HCC indicators and risk stratification of patients with chronic HBV infection are essential for guiding appropriate surveillance.Hepatocarcinogenesis as a process in individuals with chronic HBV infection is complex, and involves both host and viral factors. Various viral factors are associated with an increased risk of HCC, including HBV DNA levels, HBeAg status, HBV genotypes, pre-S deletion and mutations in the X ⁄ precore regions.Hepatitis B virus is classified into eight genotypes (A-H), based on an intergroup sequence divergence of 8% or more. HBV genotypes B and C are the predominant types in eastern Asia.(2,3) HBV genotype C is the predominant type in Korea, accounting for more than 95% of Korean chronic HBV carriers.(4,5) Several published studies indicate that carriers infected with HBV genotype C exhibit a high risk of developing HCC, (6,7) but this has not been corroborated. (8,9) In addition to HBV genotype, mutations in the X ⁄ precore regions have been associated with advancement of...

Clinical utility of complex mutations in the core promoter and proximal precore regions of the hepatitis B virus genome

“…Many additional mutants have been reported in the literature, but most of these mutations are sporadic. Our data indicate that these mutations, together with A1762T, G1764A, and G1896A, are the most important frequent mutations in HBV genotype C2 [33] . Considering the accumulation of mutations with time and the age of HCC patients, analyses must focus on the complexity of mutations associated with HCC risk, particularly in chronic HBV carriers greater than 40 years of age.…”

“…Thus, genotypes B and C are apparently aggressive with respect to the development of HCC. However, in South Korea, nearly all HBV cases are genotype C2 (Ce) [28][29][30][31][32][33] . Although highly prevalent in HCC (86%), the prevalence of the precore stop mutation does not differ significantly among chronic HBV carriers with or without HCC [32,34,35] .…”

“…Although highly prevalent in HCC (86%), the prevalence of the precore stop mutation does not differ significantly among chronic HBV carriers with or without HCC [32,34,35] . Most isolates of HBV genotype C2 in South Korea carry the T1858 mutation [32,33] , which attenuates the stability of the secondary structure of the pregenome encapsidation signal (epsilon signal). In contrast, C1858 prevents the formation of G1896A [36] .…”

“…Because the literature regarding the clinical features of wild-type HBV genotype C2 is lacking, we analyzed this genotype in comparison with three mutation types using our published raw data (n = 442) [33,37] . The selected 109 patients consisted of four groups: wild-type (Ⅰ, n = 29), precore stop mutation alone (Ⅱ, n = 14), BCP double mutation only (Ⅲ, n = 44), and the A1762T, G1764A and G1896A triple mutation (Ⅳ, n = 22).…”

Accumulation of mutations in reverse transcriptase of hepatitis B virus is associated with liver disease severity in treatment-naïve Chinese patients with chronic hepatitis B

“…11,12 Among the 8 key mutations comprising G1613A, C1653T, T1753V, A1762T, G1764A, A1846T, G1896A and G1899A in the X/preC region, a combination of ≥6 mutations shows increased risk of HCC in genotype C2 HBV infected Korean patients. 13 However, the combination of mutations in the RT region and its clinical significance have seldom been discussed.…”