Detecção da mutação FLT3-ITD por PCR e Sanger em pacientes com neoplasia mielodisplásica e leucemia mieloide aguda: aplicação diagnóstica e implementação laboratorial

Abstract

Myelodysplastic Neoplasms (MDS) are a heterogeneous group of clonal hematopoietic disorders affecting the bone marrow, predominantly in elderly patients, characterized by ineffective hematopoiesis, peripheral cytopenias, and a risk of progression to acute myeloid leukemia (AML). The FLT3-ITD mutation is one of the key factors associated with this progression, as it confers a proliferative advantage and poorer prognosis, reflecting the complexity of clonal evolution. This mutation is more frequently found in patients with the "excess blasts" subtypes (EB1 and EB2). The pathogenesis of MDS involves somatic genetic alterations, such as mutations in SF3B1, TP53, ASXL1, and FLT3, as well as immune dysregulation and chronic inflammation, linked to cellular aging. MDS is classified into subtypes by the World Health Organization (WHO), with prognosis stratified by scoring systems such as the Revised International Prognostic Scoring System (IPSS-R) and the Molecular IPSS (IPSS-M), which incorporate morphological and molecular data. Studies show that although FLT3-ITD occurs in only 2-5% of MDS cases, its presence is strongly associated with higher blast counts, poorer therapeutic response, and reduced survival. In secondary AML (sAML) evolving from MDS, this mutation is even more prevalent (20-30% of cases) and is linked to high relapse rates and chemotherapy resistance, reinforcing its role as an adverse prognostic marker. This study aimed to investigate the presence of the FLT3-ITD mutation in 45 patients diagnosed with MDS and AML, as well as the molecular mechanisms by which this mutation drives MDS progression to AML, and to validate a PCR-based protocol for FLT3-ITD detection. The mutation was identified in a 33-year-old female patient with de novo AML, confirmed by Sanger sequencing (a 27-bp insertion, 94% BLAST identity). These findings reinforce that, although rare, the FLT3-ITD mutation may be present in AML patients and, in MDS, could serve as a potential marker for disease progression and leukemic transformation.