46 Molecular Diagnosis of Entecavir Resistance into diagnostic laboratories may become useful in the future. ETV resistance, due to variations at position rt184, rt202, or rt250 alone, seems to have a minor impact on ETV susceptibility (37, 38). However, it should be considered that the addition of rtL180M and rtM204V induces a more than 70-fold decrease in ETV susceptibility; hence, the presence of variants resistant to ETV and LAM may be a factor predictive of ETV- treatment failure. The monitoring of drug-resistant variants is important for the elucidation of the prevalence and the mechanisms of resistance development and for the more effective management of treatment options; and genotypic resistance testing may be tailored to the patient’s treatment history and to the severity of the disease. References 1. European Association For The Study Of The L. EASL Clinical Practice Guidelines: management of chronic hepatitis B. J Hepatol. 2009;50(2):227-42. 2. 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