Optical Genome Mapping (OGM) is rapidly emerging as an exciting cytogenomic technology both for research and clinical purposes. In the last 2 years alone, multiple studies have demonstrated that OGM not only matches the diagnostic scope of conventional standard of care cytogenomic clinical testing but it also adds significant new information in certain cases. Since OGM consolidates the diagnostic benefits of multiple costly and laborious tests (e.g., karyotyping, fluorescence in situ hybridization, and chromosomal microarrays) in a single cost-effective assay, many clinical laboratories have started to consider utilizing OGM. In 2021, an international working group of early adopters of OGM who are experienced with routine clinical cytogenomic testing in patients with hematological neoplasms formed a consortium (International Consortium for OGM in Hematologic Malignancies, henceforth "the Consortium") to create a consensus framework for implementation of OGM in a clinical setting. The focus of the Consortium is to provide guidance for laboratories implementing OGM in three specific areas: validation, quality control and analysis and interpretation of variants. Since OGM is a complex technology with many variables, we felt that by consolidating our collective experience, we could provide a practical and useful tool for uniform implementation of OGM in hematologic malignancies with the ultimate goal of achieving globally accepted standards.

The latest updates to the classification of hematolymphoid malignancies using the World Health Organization (WHO, 5th ed.) and ICC (International Consensus Classification) criteria highlight the critical need for comprehensive and precise cytogenomic data for diagnosis, prognostication, and treatment. This presents significant challenges for clinical laboratories, requiring a complex workflow using multiple assays to detect different types of structural chromosomal variants (copy number changes, fusions, inversions) across the entire genome. Optical genome mapping (OGM) is an advanced cytogenomic tool for genome‐wide detection of structural chromosomal alterations at the gene/exon level. Studies demonstrate that OGM facilitates the identification of novel cytogenomic biomarkers, improves risk stratification, and expands therapeutic targets and personalized treatment strategies. OGM is easy to implement and highly accurate in detecting structural variants (SVs) across various diagnostic entities. Consequently, many centers are integrating OGM into the clinical cytogenetic workflow for hematological malignancies. However, systemic clinical adoption has remained limited due to the lack of expert recommendations on clinical indications, testing algorithms, and result interpretation. To address this, experts from the International Consortium for OGM and relevant multidisciplinary fields developed recommendations for the integration of OGM as a standard‐of‐care cytogenetic assay for the diagnostic workflow in various clinical settings. These recommendations standardize the use of OGM across laboratories, ensure high‐quality cytogenetic data, guide clinical trial design and development, and provide a basis for updates to diagnostic and classification models.

Philadelphia (Ph)-like acute lymphoblastic leukemia (ALL) is a molecular subtype of high-risk B-cell ALL characterized by formation of abnormal gene fusions involving tyrosine kinase (TK) and cytokine receptor genes and activation of TK signaling. Because of the diversity of associated genetic changes, the detection of Ph-like ALL cases currently requires multiple cytogenetic and molecular assays; thus, our goal was to develop a consolidated workflow for detecting genetic abnormalities in Ph-like ALL. We found that total and targeted RNA sequencing (RNAseq)-based approach allowed the detection of abnormal fusion transcripts (EBF1-PDGFRB, P2RY8-CRLF2, RCSD1-ABL1, and RCSD1-ABL2). The bioinformatics algorithm accurately detected the fusion transcripts without prior input about possible events. Additionally, we showed that RNAseq analysis enabled evaluation for disease-associated sequence variants in expressed transcripts. While total RNAseq can be a second tier approach allowing discovery of novel genetic alterations, the targeted RNAseq workflow offers a clinically applicable method for the detection of fusion transcripts.