Key Clinical Summary

• Broad next-generation sequencing (NGS) is increasingly essential for evaluating unexplained cytopenias, clonal hematopoiesis, and suspected bone marrow failure syndromes.
• Molecular results frequently refine or change diagnoses, distinguishing between Clonal cytopenia of undetermined significance (CCUS), myelodysplastic syndromes (MDS), inherited marrow failure, and immune-mediated etiologies.
• Genetic testing for hereditary anemia reveals frequent misclassification, reinforcing the need for phenotype–genotype correlation and careful selection of molecular assays.

At the 67th ASH Annual Meeting and Exposition, experts presented updates on the role of molecular diagnostics in classical hematology. Speakers emphasized that NGS is transforming diagnostic strategies for cytopenias, bone marrow failure, and hereditary red cell disorders. The session highlighted how precise genomic interpretation—paired with clinical and laboratory evaluation—improves diagnostic accuracy, guides therapy, and informs referral to genetics.

Session Highlights

Uma Borate, MD, MSc, The Ohio State University, opened with a framework for evaluating cytopenias and bone marrow failure using molecular tools. She underscored that NGS should be strongly considered when performing bone marrow biopsies for unexplained cytopenias. Evidence from European cohorts demonstrates that NGS clarified or reclassified diagnoses—such as MDS or acute myeloid leukemia (AML)—in approximately 20% of ambiguous cases.

Dr Borate detailed the continuum from clonal hematopoiesis (CH/CHIP) to CCUS and ultimately myeloid malignancy. She emphasized careful interpretation of variant allele frequency (VAF): small DNMT3A or TET2 clones (2% to 5% VAF) rarely explain severe anemia, whereas spliceosome mutations and high MCV/RDW strongly predict CCUS or early MDS. Newly validated risk calculators (A-CCRS and CHRS) help estimate progression risk based on mutation burden, platelet counts, and spliceosome involvement.

She further highlighted the importance of distinguishing inherited bone marrow failure syndromes (IBMFS) from aplastic anemia or hypoplastic MDS. NGS often uncovers germline predisposition genes—including DDX41, Fanconi, and telomere biology genes—that alter transplant decisions, donor selection, and long-term surveillance.

Xiao Peng, MD, PhD, Children’s Hospital at Montefiore, shifted to a conceptual exploration of how genomics reshapes disease classification. She emphasized matching pathobiology, not symptoms, to genetic testing strategy. Many immune-mediated cytopenias arise from defects in innate immunity, metabolism, or double-strand break repair, not solely adaptive immune pathways.

Dr Peng stressed limitations of panel-based testing: high-homology regions, noncoding variants, structural variants, and mosaicism frequently evade detection. She advocated broad first-line NGS (exome/genome) for suspected genetically driven disease due to extensive heterogeneity and evolving gene–disease relationships. Functional immunologic assays remain crucial for resolving variants of uncertain significance (VUS) and avoiding misinterpretation.

Theodosia Kalfa, MD, PhD, Cincinnati Children’s Hospital, presented “molecular surprises” in diagnosing hereditary anemias. She showcased cases where patients labeled with congenital dyserythropoietic anemia (CDA) were later found—via whole genome sequencing (WGS) and functional studies—to have beta-thalassemia variants, pyruvate kinase deficiency, or hereditary xerocytosis (HX). She stressed prioritizing globin gene sequencing in microcytic anemia and using ektacytometry to differentiate red cell membrane disorders. Genetic clarification frequently prevented harmful interventions (eg, splenectomy in HX) and uncovered significant iron overload requiring urgent management.

According to Dr Borate, integrating molecular results requires “clinical context above all,” particularly for small clonal hematopoiesis (CH) clones that may not explain cytopenias. She noted that negative marrow NGS has a high negative predictive value for myeloid malignancy, reducing diagnostic uncertainty.

Dr Peng emphasized multidisciplinary collaboration, cautioning clinicians not to overinterpret incidental findings or assume germline status from somatic panels. “We treat patients—not genotypes,” she said, underscoring the risk of inappropriate labeling and unnecessary anxiety.

Dr Kalfa highlighted the continued importance of phenotype-driven evaluation. Even “gold-standard” tests like bone marrow biopsy can mislead without molecular correlation. She urged clinicians to avoid irreversible procedures until genetic clarification is obtained and reminded attendees that rare disorders require systematic, multimodal evaluation.

Implications for Practice

The session reinforces that NGS is now central to evaluating cytopenias, bone marrow failure, and hereditary anemia. Clinicians should select assays based on suspected pathobiology and understand panel limitations. Accurate molecular classification enables appropriate therapy selection, transplant planning, surveillance, and referral to genetics while preventing misdiagnosis and unnecessary procedures.

Conclusion

Molecular diagnostics continue to reshape classical hematology. As testing expands, clinicians must integrate genomic data with careful phenotyping and interdisciplinary input. Ongoing research, broader panels, and improved analytics will further refine diagnostic precision and patient care.

Reference

Borate U, Peng X, Kalfa T. Molecular diagnostics for clinical classical hematologists: when to order, what to order, what it means, and when to refer to genetics? Presented at: ASH 2025; December 6-9; Orlando, FL.