Advances in molecular diagnostics for hematopoietic and lymphocytic neoplasms

Advances in molecular diagnostics for hematopoietic and lymphocytic neoplasms

Hematopoietic and lymphocytic neoplasms (HLNs) are a diverse group of malignancies affecting blood and lymphatic systems, with outcomes varying from manageable conditions to fatal diseases. Traditional classifications rely on morphology, karyotyping and fluorescence in situ hybridization (FISH). However, recent advances in next-generation sequencing (NGS) enable simultaneous genetic profiling of multiple genes, improving diagnostic precision and therapeutic strategies. This review explores key molecular applications in the diagnosis and management of HLNs, addresses current challenges, and proposes solutions to optimize clinical utility.

Chronic myeloid leukemia (CML)

CML, historically identified by leukocytosis, is characterized by the BCR::ABL1 fusion gene, which results from the Philadelphia chromosome translocation. This oncogenic fusion drives aberrant tyrosine kinase activity and promotes unchecked proliferation. The introduction of imatinib, a targeted tyrosine kinase inhibitor (TKI), revolutionized CML treatment, resulting in normalized white blood cells (WBC) within months. However, resistance mutations require molecular monitoring via quantitative PCR, FISH and karyotyping to ensure optimal therapeutic adjustments.

Molecular applications in BCR::aBL1-negative myeloid neoplasms

Certain myeloid neoplasms, such as chronic neutrophilic leukemia (CNL) and chronic eosinophilic leukemia (CEL), have the BCR::ABL1 fusion gene but different genetic markers such as CSF3R mutations in CNL. Classic myeloproliferative neoplasms (MPNs) include polycythemia vera, essential thrombocythemia, and primary myelofibrosis, which are driven by JAK2, MPL, or CALR mutations. The use of NGS enables comprehensive mutation profiling that supports accurate diagnosis and prognosis.

Genetic abnormalities in myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase fusion genes

This newly classified subgroup within WHOEM5 includes cases with eosinophilia driven by tyrosine kinase fusion genes such as PDGFRA, PDGFRB and FGFR1. Rapid molecular diagnostics are crucial because imatinib-sensitive fusions lead to favorable outcomes. Fish and targeted sequencing facilitate precise identification and treatment selection.

Genetic abnormalities in myelodysplastic syndromes (MDs) and MDS/MPN

MDS is defined by cytopenia, morphologic dysplasia, and potential progression to acute myeloid leukemia (AML). Genetic abnormalities including deletions (5q, 7q, 20q) and mutations in splicing genes (SF3B1, SRSF2), epigenetic regulators (ASXL1, TET2) and tumor suppressors (TP53), prognosis and therapeutic strategies. In MDS/MPN, mutations in genes such as ETNK1 and SETBP1 further advance diagnostic and risk stratification approaches.

Genetic abnormalities in AML and diagnostic approaches

AML is a highly heterogeneous disease, with approximately 50% of cases presenting with chromosomal abnormalities. Favorable mutations include PML::RARA and Runx1::Runx1t1, while undesirable mutations include TP53, FLT3 and KMT2A rearrangements. The use of cytogenetics, fish and NGS panels supports classification, prognosis and treatment selection. The emergence of targeted therapies against FLT3 and IDH1/2 mutations highlights the clinical impact of molecular profiling.

Genetic abnormalities in B and T cell lymphoproliferative disorders (LPDs) and lymphomas

Chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL)CLL/SLL prognosis is closely linked to IGVH mutation status, with hypermutated IGVH correlating with better outcomes. Cytogenetic abnormalities such as deletions (13q-, 11q-, 17p-) and mutations in TP53 and Notch1 influence therapeutic strategies. The introduction of Bruton's tyrosine kinase (BTK) inhibitors such as ibrutinib has transformed treatment, although resistance mutations (BTK C481s) require molecular monitoring.

Low-grade and high-grade B-cell lymphomasLow-grade lymphomas, including follicular lymphoma and mantle cell lymphoma, often have BCL2, BCL6, or CCND1 translocations. Burkitt's lymphoma is driven by Myc rearrangements, which is confirmed via fish. In high-grade B-cell lymphomas, simultaneous rearrangements of Myc and BCl2/BCL6 define “double hit” lymphomas that require aggressive treatment. Emerging mutational profiling stratifies large B-cell lymphoma (DLBCL) into prognostic subtypes.

T-cell lymphomasT-cell lymphomas show various genetic aberrations with Alk rearrangements that define anaplastic large cell lymphoma. Mutations in RhoA, IDH2 and STAT3/5b influence on peripheral T-cell lymphoma and the classification of large granular lymphocytic leukemia. Clonal T cell receptor gene (TCR) gene rearrangement detection remains crucial in distinguishing reactive from neoplastic processes.

Conclusions

Molecular genetic testing has revolutionized the diagnosis and treatment of hematopoietic and lymphocytic neoplasms. High-throughput sequencing technologies coupled with bioinformatics advances, improving disease classification, risk stratification and personalized treatment selection. Ongoing research aims to refine molecular assays and develop novel targeted therapies, ultimately improving patient outcomes.

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