[Genetic characteristics and survival analysis of 27 cases of juvenile myelomonocytic leukemia]

Objective: To investigate the genetic and genomic profiling of juvenile myelomonocytic leukemia (JMML) and factors affecting its survival rate. Methods: Clinical characteristics, cytogenetics, molecular biology results and survival status of children with 27 JMML cases admitted to the Hematology Department of Children's Hospital, Capital Institute of Pediatrics from December 2012 to December 2021 were analyzed retrospectively, and the outcomes of the children were followed up. Kaplan-Meier method was used for survival analysis. Univariate analysis was used for analyzing factors affecting the overall survival (OS) rates of patients who received hematopoietic stem cell transplantation (HSCT). Log-Rank test was used for comparison of survival curves. Results: Among 27 JMML cases, there were 11 males and 16 females. The age of disease onset was 28 (11,52) months. There are 20 cases of normal karyotype, 4 cases of monosomy 7, 1 case of trisomy 8,1 case of 11q23 rearrangement and 1 case of complex karyotype. A total of 39 somatic mutations were detected.Those involved in RAS signal pathway were the highest (64%(25/39)), among which PTPN11 mutation was the most frequent (44% (11/25)). A total of 17 cases (63%) received HSCT, 8 cases (30%) did not receive HSCT, and 2 cases (7%) lost follow-up. For children receiving transplantation, the follow-up time after transplantation was 47 (11,57) months. The 1-year OS rate of high-risk transplantation group (17 cases) and high-risk non transplantation group (6 cases) was (88±8)% and (50±20)% respectively, with a statistically significant difference (χ²=5.01, P=0.025). The 5-year OS rate of the high-risk transplantation group was (75±11)%. The survival time of those who relapsed or progressed to acute myeloid leukemia after transplantation was significantly shorter than that of those who did not relapse (χ²=6.80, P=0.009). The OS rate of patients with or without PTPN11 mutation was (81±12) % and (67±19)% respectively (χ²=0.85, P=0.356). Conclusions: The main pathogenesis involved in JMML is gene mutation related to RAS signaling pathway, and the most common driver gene of mutation is PTPN11. Allogeneic HSCT can significantly improve the survival rate of high-risk JMML patients. The recurrence or progression after transplantation was related to poor prognosis.