Objective To investigate the expression and significance of mRNAand exon mutationof NT5C2 gene in acute lymphoblastic leukemia (ALL) bone marrow.Methods Case control study design was used in this study.Bone marrow samples were collected from ALL patients in Anhui Provincial Cancer Hospital in recent 4 years.The patientswere divided into the initial diagnosis group , the complete remission group and the recurrence group.And they could specifically be divided into 36 patients initially diagnosed, 36 patients who achievedcomplete remission and 16 patients who relapsed with children B -ALL,15 patients initially diagnosed,15 patients who achievedcomplete remission and 9 patients who relapsed with children T -ALL, 18 patients initially diagnosed,18 patients who achievedcomplete remission and 12 patients who relapsed with adult B-ALL, and 11 patients initially diagnosed,11 patients who achievedcomplete remission and 6 patients who relapsed with adult B -ALL.The initial diagnosis,complete remission and recurrence samples were matched.8 children and 8 adults without hematologic malignanciewere used as controls .Real-time PCR was performed to detect the level of NT5C2 mRNAin ALL patients.The exons of NT5C2 gene were cloned and sequenced for the common mutations in all cases .The results of NT5C2 mRNA levels in different groups were performed using non -parametric test by SPSS16.0 analytics software, and then non-parametric test together with correlation analysis was analyzed between NT 5C2 mRNA levels of different initial diagnosis groups and gender, age, leukocyte level and risk classification .Results (1)The expression of NT5C2 mRNA levels of recurrence group were higher than that of initial diagnosis group ,complete remission group and controls in children and adult B -ALL respectively(P <0.01).(2)NT5C2 mRNA expression in children and adult T-ALL showed no difference in initial diagnosis ,complete remission, recurrence group and controls (P >0.05).(3)NT5C2 mRNA expression of initial diagnosis group in children and adult B -ALL and T-ALL was not correlated with risk classification (P >0.05).(4)A newheterozygousmutation p.P414A of NT5C2 was discovered in a recurrencesample.Conclusions (1) High expression ofNT5C2 mRNA is associated with recurrence inchildren and adult B-ALL, and it may be an indicator of monitoring recurrence .(2)The incidence of exons mutation of NT5C2 gene in ALL is low in China.