1.What are the symptoms of drug resistance to a nucleoside analog? Taking nucleoside analogs need to be checked regularly for HBVDNA quantification (generally 3 months-6 months), if HBVDNA is found to be elevated again, or accompanied by liver function abnormalities, it is necessary to consider whether drug resistance has occurred. 2. Many patients have to do a drug resistance gene test, what is the significance and purpose of this test? The purpose of drug resistance test is to further clarify whether there is drug resistance; if there is drug resistance, you can see the resistant viral locus, which can help guide the selection of antiviral drugs in the future, avoiding the application of drugs that are already resistant and improving the effect of antiviral therapy. 3.If the patient does not have a timely review, is it possible that the patient is already resistant to the drug but does not know it? What happens if the drug resistance is already present but not detected in time? Will there be a serious situation? Without timely review, it is possible to be unaware of the viral mutation that has already occurred, and consult the doctor only when the viral mutation has led to an aggravation of the clinical condition, which often delays the treatment, and may lead to severe hepatitis attack if the underlying liver condition is poor.