Hepatitis B virus genotype distribution and mutation patterns: Insights and clinical implications for hepatitis B virus positive patients

Table 1 It shows mutation impact on hepatitis B virus and its clinical consequences

Region	Effect on hepatitis B virus	Clinical consequences
Pre-S region	Impaired secretion, immune escape	Increased HCC risk, occult infections
S region	Altered hepatitis B surface antigen structure	Diagnostic failures, vaccine escape
Basalcore promoter region	Reduced HBeAg, increased replication	Severe liver disease, HCC
Precore region	Loss of HBeAg	Silent chronic infection, higher liver inflammation
Polymerase region	Antiviral resistance	Treatment failure, persistent viremia
X gene	Enhanced oncogenesis	Direct contribution to HCC

HbeAg: Hepatitis B e antigen; HCC: Hepatocellular carcinoma.

Table 2 It shows common mutations in hepatitis B virus genome

No.	Mutation	Location	Effect	Clinical significance	Impact on treatment
1	G1896A	Pre-core	Defective HBeAg production	HBeAg-negative chronic hepatitis B	May affect serological monitoring
2	G145R, T126I	S region	Immuneand diagnostic escape	Occult infections, vaccine breakthrough	May affect serological monitoring
3	A1762T/G1764A	Core promoter	Higherviral replication	Increased risk of liverdisease progression	Requires close monitoring
4	RtM204V/I	Polymerase	Lamivudine resistance	Viral rebound and liver disease progression	Reduced efficacy of lamivudine and potential cross-resistance
5	RtI169T, rtT184G, rtS202I, rtM250V	Polymerase	Entecavir resistance	Necessitates alternative therapies	Reduced efficacy of entecavir
6	RtA194T	Polymerase	Tenofovir resistance	Complicates treatment strategies	Reduced susceptibility to tenofovir, especially with priorlamivudine exposure
7	K130M, V131I	X gene	Adefovir resistance	Enhances viral replication and transcription	These mutations stabilizes the virus under drug pressure

HbeAg: Hepatitis B e antigen.