Characteristics of DNMT3a mutation in acute myeloid leukemia and its prognostic implication

Abstract

Acute myeloid leukemia (AML) is a clonal disorder arising from the differentiation arrest of myeloid precursor and malignant proliferation of a bone marrow derived, self-renewing stem or progenitor cells inside the bone marrow (BM) and blood due to numerous genetic mutations. Some mutations can also adjust DNA methylation and may play a critical function in pathogenesis in Cytogenetically Normal Acute Myeloid Leukemia (CN-AML). Somatic mutations in DNMT3a were pronounced in approximately 20% and ∼30–35% of overall AML and CN-AML, respectively. Most DNMT3a mutations in AML have been observed to be heterozygous, A missense mutation, R882, located inside Hot spot exon 23, has been found to be the maximum common mutation. This is a preliminary study conducted on 20 adult Egyptian patients newly diagnosed as AML where Sanger sequencing of Hotspot Exon 23 of DNMT3a gene was performed on their initial bone marrow samples and were followed up to 3 months post-induction therapy. Only De Novo AML patients were included in our study. Our results revealed that overall DNMT3a mutations were present in 25% of our patients, 10% having the R882 (rs147001633) mutation being 5% R882C and 5% R882H. Immunophenotyping analysis among Mutated DNMT3a (R882 and Non R882) and Wild DNMT3a revealed that AML markers exhibited no significant differences except for myeloperoxidase positivity which was significant among the groups (0.050). Regarding cytogenetics, only one case of the mutated DNMT3a had positive FISH inv (16), where the rest were FISH negative. After 28 days of induction, 75% of all our patients achieved complete response (CR), 20% achieve partial response (PR) out of which 75% are DNMT3a mutated. After 3 months follow-up, 10% of all patients faced mortality where 5% was DNMT3a wild type (died due to treatment-related mortality) and 5% was R882 mutated DNMT3a. DNMT3a mutations are present in 25% (5/20) of our AML patients, with 10% (2/20) having the R882 mutation being 5% (1/20) R882C and 5% (1/20) R882H. R882 mutation is associated with resistance to chemotherapy, and poorer outcomes, highlighting its poorer prognostic significance in AML.