Naturally occurring hepatitis B virus reverse transcriptase mutations related to potential antiviral drug resistance and liver disease progression

Table 4 Variation in the prevalence of preexisting reverse transcriptase mutations according to mutation detection methods, genotype, and geographic distribution

Prevalence	Location	No. of cases	Genotype	HBV DNA loads (log10 IU/mL)	RT mutations prevalence	Mutation detecting methods	Ref.
HBV DNA RT mutations ≥ 5%	Italy	255	A, C, D	5.0	5.0% mutations overall	INNO-Lipa HBV DR v.3	[25]
	China	269	B, C, B-C	4.9	8.9% mutations overall	INNO-Lipa HBV DR v.3	[27]
	Canada	209	A, B, C, D	7.0	12% M204I/V, 10% L180M, 9% L80V/I, 3%V173L	INNO-Lipa HBV DR v.3	[24]
	Turkey	71	NA	NA	18.3% YMDD mutations	INNO-Lipa HBV DR v.1	[28]
	South Korea	131	C2	6.5	12.98% mutations overall	Direct Sequencing	[33]
	Turkey	77	D	7.3	7.8% YMDD mutations	Direct Sequencing	[36]
	China	213	B, C	6.2	6.1% mutations overall	Direct Sequencing	[47]
	China	104	B, C, B-C	4.5	26.9% YMDD mutations	Direct Sequencing	[93]
	Japan	18	NA	NA	27.8% YMDD mutations	Direct Sequencing	[34]
	Iran	325	D	NA	15.69% mutations overall	Direct Sequencing	[50]
	Taiwan, China	28	NA	7.5	57% YMDD mutations	Direct Sequencing	[35]
	China	357	B, C	6.3	16.8% mutations overall	Direct Sequencing	[39]
	Meta-analysis (China)	8156	B, C, D	NA	8.00% mutations overall	Record screening	[73]
	Japan	14	B, C	4.9	35.7% YMDD mutations	Ultra-deep sequencing	[94]
HBV DNA RT mutations < 5%	Iran	147	D	NA	None	Direct sequencing	[56]
	China	328	B, C	6.9	3.6% mutations overall	Direct sequencing	[53]
	Japan	20	NA	NA	None	Direct sequencing	[48]
	California	472	A, B, C, D, F	5.3	< 1% mutations overall	Direct sequencing	[45]
	Italy	100	NA	NA	None	Direct sequencing	[49]
	Italy	140	D	4.0	3.5% mutations overall	Direct sequencing	[51]
	Germany	96	A, D	NA	None	Direct sequencing	[32]
	Brazil	189	A, C, D, F	3.2	overall 6.0% in Northeast/ 0% in North	Direct sequencing	[41]
	California	198	B, C	4.2	1% mutations in polymerase	INNO-Lipa HBV DR v.3	[26]