Analysis of hepatitis B virus gene mutation pattern of 444 cases of lamivudine-resistant patients

Objective To study the patterns and characteristics of YMDD motif mutation in hepatitis B virus(HBV) polymerase gene in patients with drug-resistance during lamivudine treat- ment.Methods Four hundreds and forty four patients with chronic hepatitis B who exhibited drug- resistant mutation during lamivudine treatment were retrospectively analyzed.YMDD motif mutation types were determined by gene chips,and the characteristics of different types of YMDD motif muta- tion were analyzed.Results There were 185 cases of YVDD mutation,216 cases of YIDD mutation and 43 cases of YVDD+YIDD mutation among 444 patients.Rate of combination of an additional L180M mutation of them were 50.81%(94 cases),15.74% (34 cases) and 41.86% (18 cases),re- spectively.Compared with YVDD mutants,the detection rate of YIDD mutants were higher and it oc- curred in older patients,mutated later,its serum HBV DNA level was higher,and the flare of hepati- tis was more severe.YMDD mutation with L180M emerged earlier and had higher levels of serum HBV DNA than YMDD mutation only.Conclusions Point mutation and combined mutation are dominant in YMDD mutation patterns.YIDD mutation is dominant in point mutation and YVDD combined with L180M mutation is dominant in combination mutation.The clinical manifestations are different in patients with dif- ferent types of YMDD mutation.The type of YMDD motif mutants can affect the clinical prognosis and therapeutic effects.