Analysis of Gene Mutation and Clinical Characteristics in 19 Children with Juvenile Myelomonocytic Leukemia

Abstract

To analyze the gene mutations of children with juvenile myelomonocytic leukemia (JMML) and their correlation with clinical characteristics. The genetic mutation results and clinical data of 19 children with JMML in Fujian from January 2015 to December 2018 were collected and analyzed retrospectively. According to the results of gene mutation, they were divided into PTPN11 gene mutation group and non-PTPN11 gene mutation group, and the clinical characteristics and prognosis of children with JMML between two groups were compared. Among the 19 children with JMML, 14 cases were male and 5 cases were female, and male/female ratio was 2.8∶1. The median age at diagnosis was 13(3-48) months, and 14 cases (73.68%) were less than 2 years old. Abdominal distension and pyrexia were the common initial symptoms, and all the children with JMML had splenomegaly. The median white blood cell count was 39.82(4.53-103.4)×109/L，and monocyte count was 4.37(1.04-23.12)×109/L. HbF was higher than the normal high value of the same age in 8 cases (42.11%). All JMML children's Philadelphia chromosome and BCR-ABL1 fusion gene were negative. Among the 19 patients, there were 1 case without any JMML related gene mutation, 7 cases (36.84%) with PTPN11 mutation, 6 cases (31.58%) with K-Ras mutation, 2 cases with NF1 mutation (10.53%), 2 cases with N-Ras mutation (10.53%), and 1 case (5.26%) with NF1 and N-Ras mutations simultaneously. Fifteen patients who only received supporting therapy all died, with a median survival time 9.2 (0.4-58.1) months. Whereas, among the four JMML children who received hematopoietic stem cell transplantation(HSCT), three cases survived and only one case died. Compared with the non-PTPN11 gene mutation group, the proportion of patients with hemoglobin F higher than the normal value of the same age was higher, and the median survival time was shorter in PTPN11 gene mutation group, and the differences were statistically significant (P=0.048 and 0.046, respectively). JMML is more common in male infancy and toddlerhood, and the main gene mutation types are PTPN11 and Ras mutations. Because the JMML children with PTPN11 mutations show particularly rapid disease progression, if there is no timely intervention, most children die in a short period of time. Therefore, early HSCT may improve the prognosis of the children with JMML.