Pedigree Investigation, Clinical Characteristics and Prognosis Analysis of Hematological Disease Patients with Germline TET2 Mutation

Abstract Background: More and more germline gene mutations have been discovered in hematological malignances with the development of next gene sequencing (NGS). Tet methylcytosine dioxygenase 2 (TET2) is one of the most common mutation genes in hematological neoplasms. We aimed to analyzed whether germline TET2 mutation has a family aggregation or is a tumor predisposition gene. Further we compared its impact with somatic TET2 mutation in hematological diseases.Methods: A total cohort of 103 hematological patients with TET2 mutation were included from December 2016 to December 2019. Data were extracted from hematology department of West China Hospital of Sichuan University. Bone marrow (BM) or peripheral blood (PB) as somatic DNA origin to be detected by next-generation sequencing (NGS), and nails and hairs as germline DNA origin to be detected by Sanger sequencing, respectively. Further, we compared the clinical characteristics between the patients with germline and somatic TET2 mutation.Results: 103 patients were included, including 33 (32.03%) patients with germline TET2 mutation and 70 (67.97%) patients with somatic TET2 mutation. Variant allele frequency (VAF) of germline TET2 mutation was more stable in our study, ranging from 40% to 55% and mutation sites were more concentrated. Patients with germline TET2 mutation were younger with median age 48 (range, 16-82) (P=0.0078). Further, patients with germline TET2 mutation were mainly myelodysplastic syndromes (MDS) (n=13, 39.4%), while patients with somatic TET2 mutation were acute myeloid leukemia (AML) (n=28, 40.0%) (P=0.0003). Germline TET2 mutation affected the distribution of peripheral blood cell count and the proportion in bone marrow (P<0.05). Germline TET2 mutation was a poor prognosis factor in MDS patients via univariate analysis (HR=5.3, 95%CI: 0.89-32.2, P=0.0209), but not in multivariate analysis by Cox regression model (P=0.062).Conclusions: Some family members were asymptomatic carriers, which indicated germline TET2 mutation might have a family aggregation. More importantly, TET2 gene may be a predisposition gene of hematological malignant when the other gene mutations as the second hit. The VAF of germline TET2 mutation is more stable. At the same time, the germline TET2 mutation may be an adverse factor for the MDS patients.