2015 Volume 56 Issue 9 Pages 482-484
Entecavir was approved as a drug for chronic hepatitis B. However, hepatitis B virus (HBV) may acquire drug resistance. For entecavir (drug) resistance (ETVr), another mutation (rt184, rt202, or rt250) must be acquired in addition to lamivudine (LAM)-resistant mutations (rtL180M and rtM204V). We performed HBV DNA sequencing in a LAM-resistant patient with viral breakthrough after the administration of entecavir for 27 months. In this patient, previously-reported ETVr mutants at the position of rt184, rt202, or rt250 were not found, but a mutation rtA186T was observed with LAM resistance (rtL180M and rtM204V). As it is difficult to evaluate rtA186T mutation using commercially available assays in Japan, it would be important to recognize it as a new resistant mutation.
