Nijmegen breakage syndrome (NBS) is a rare autosomal recessive disorder. Epidemiological data evidence that NBS1 gene can be considered a susceptibility factor for cancer development.So far nine mutations localized in coding sequence of the NBS1 gene have been found at the heterozygous state in cancer patients,the 6S7del5,511A→C (I171V), 643C→T(R215W) are the most frequently described. The review will focus on the symptoms of NBS characteristics, the recent advances of NBS1 gene producethe correlation between carriers of NBS1 gene frequent heterozygous mutations and the development of malignant tumours.

Objective:To assess the clinical significance of next-generation sequencing (NGS)-based IGH/ IGK gene rearrangement analysis versus flow cytometry (FCM) in diagnosing minimal residual disease (MRD) of children with acute B-cell lymphoblastic leukemia (B-ALL). Methods:Clinical data, NGS-MRD and FCM-MRD findings at the initial diagnosis and after induction chemotherapy of 85 children diagnosed as B-ALL in Children′s Hospital of Nanjing Medical University from July 2019 to July 2021, were retrospectively analyzed.The sensitivity of the two methods, and the positive rate were compared by χ2 test or Fisher′ s test.The correlation was identified by Spearman correlation analysis. Results:Dominant clone sequences were detected in all children at the initial diagnosis by NGS, while selection markers were identified by FCM in 75(88.2%) patients.Positive MRD rate detected by NGS-MRD was significantly higher than that of FCM-MRD at the same time point after induction chemotherapy[31.8%(27/85) vs.9.4%(8/85), P<0.001]. Compared with those of FCM-MRD, NGS-MRD had good sensitivity (100.0%), specificity (75.3%) and negative predictive value (100.0%), and the positive predictive value was 29.6%.MRD results detected by NGS were consistent with that of FCM ( r=0.569, P<0.001). By July 27, 2022, 2 patients with NGS-MRD (+ )FCM-MRD (-)relapsed during maintenance chemotherapy. Conclusions:NGS is highly consistent with FCM in the detection of MRD in children with B-ALL, which is more sensitive.The combination of NGS-MRD and FCM-MRD benefits more in monitoring MRD in children with B-ALL after induction chemotherapy.