Zou, Ying

Background/Objective: Although most melanocytic lesions are diagnosed as benign or malignant by histopathologic evaluation, with or without the aid of immunohistochemistry, diagnosis may remain uncertain in a minority of cases. Assessment of copy number abnormalities (CNAs) may provide sufficient additional evidence to favor either a benign or malignant diagnosis in both pediatric and adult cases and in melanocytic lesions of various subtypes, including Spitzoid, mucosal, and acral. CNAs are common in melanomas, while they are rare, with few exceptions, in benign lesions. Detection of CNAs by fluorescence in situ hybridization (FISH) and chromosomal microarray (CMA) has been well established for melanocytic lesions, with advantages and disadvantages for each. The objective of this meta-analysis was to evaluate the utility of CNA testing for the diagnosis of melanoma, across subtypes, when a lesion remains ambiguous after histopathologic and immunohistochemical assessment. In addition, the utility of CNAs to determine prognosis in established diagnoses of melanoma was also evaluated. Methods: The Cancer Genomics Consortium Working Group for Melanocytic Lesions reviewed published data from January 1998 through September 2022 of CNAs in melanocytic lesions detected by either FISH or CMA and conducted a meta-analysis of the findings. Results: Specific abnormalities common in primary cutaneous melanomas of various subtypes and uveal melanomas were enumerated. Differences in CNAs found in primary versus metastatic lesions were also determined, and published evidence for prognosis was summarized. Conclusions: The working group established evidence-based recommendations for the use of CNA testing for evaluation of ambiguous melanocytic lesions.

Context.— Optical genome mapping (OGM) represents a promising cytogenomic technology that detects structural variants, including fusions, rearrangements, copy number variants, and loss of heterozygosity, in a single assay. Unlike karyotyping, fluorescence in situ hybridization, or chromosomal microarray, OGM leverages long-molecule imaging to map the whole genome with high resolution. This positions OGM as a novel tool for constitutional and somatic/cancer genomics. However, its current and planned utilization in clinical and research settings remains unknown, necessitating further investigation. Objective.— To investigate the current utilization of OGM in clinical and research laboratories, assess its applications, and evaluate future utilization strategies. Design.— In 2024, a supplemental questionnaire was incorporated into 6 College of American Pathologists proficiency testing programs to evaluate OGM’s utilization. Results.— Of 921 returned questionnaires, 712 were analyzed after duplicates were removed. Sixty-seven (9.4%) currently offered OGM testing: 5.2% (37) for research only, 1.8% (13) for only clinical use, and 2.4% (17) for both. Future adoption plans showed 7.6% (53 of 700 laboratories) and 7.9% (55 of 700 laboratories) aiming to implement OGM clinically within 12 and 24 months, respectively. The most common applications included hematologic malignancies and constitutional/germline postnatal disorders, followed by prenatal testing. International laboratories demonstrated statistically higher utilization rates than domestic laboratories ( P = .001). Conclusions.— This first survey on OGM clinical utilization reveals its status as a niche technology, with 67 laboratories currently using it. Its primary clinical applications are in constitutional/germline analysis and hematologic malignancies. Although international laboratories led in 2024, 108 laboratories (domestic and international) plan clinical adoption within 24 months, signaling OGM’s potential for broader integration.

Background: The joint College of American Pathologists/American College of Medical Genetics and Genomics Cytogenetics Committee works to ensure the competency and proficiency of clinical cytogenetic testing laboratories through proficiency testing (PT) programs for various clinical tests offered by such laboratories, including the evaluation of cytogenetic abnormalities in solid tumors. Methods: Review and analyze 25 years (1999–2023) of solid tumor chromosome analysis PT results, utilizing G-banded karyograms. A retrospective review of results from 1999 to 2023 was performed, identifying the challenges addressing solid tumors. The chromosomal abnormalities and overall performance were evaluated. Results: A total of 21 solid tumor challenges were administered during the period 1999–2018. No solid tumor challenges were administered during the period 2019–2023. Challenges consisted of metaphase images and accompanying clinical history for the evaluation of numerical and/or structural abnormalities. All 21 cases reached 80% grading consensus for abnormality recognition. However, five cases (24%) failed to reach consensus for nomenclature reporting by participating laboratories. These cases illustrate errors in reporting chromosomal abnormalities, including whole-arm translocations and those involving sex chromosomes. In addition, they highlight the challenges with differentiation of terminal and interstitial deletions, difficulties in identifying correct breakpoints, and omission of brackets in neoplastic cases. Conclusions: This comprehensive 25-year review demonstrates the exceptional proficiency of cytogenetic laboratories in accurately identifying chromosome abnormalities in solid tumors, while also highlighting the challenges of reporting specific types of chromosomal abnormalities.

Context.— The joint College of American Pathologists/American College of Medical Genetics and Genomics Cytogenetics Committee works to ensure competency and proficiency of clinical cytogenetics testing laboratories through proficiency testing programs for various clinical tests offered by such laboratories, including the evaluation of constitutional abnormalities. Objective.— To review and analyze 20 years of constitutional chromosome analysis proficiency testing results (2003–2022), primarily utilizing G-banded karyograms. Design.— A retrospective review of results from 2003 through 2022 was performed, identifying challenges addressing constitutional disorders. The chromosomal abnormalities and overall performance were evaluated. Results.— A total of 184 cases from 161 proficiency testing challenges were administered from 2003 through 2022. Challenges consisted of metaphase images and accompanying clinical history for evaluation of numerical and/or structural abnormalities. Of the 184 cases, only 2 (1%) failed to reach an 80% grading consensus for recognition of the abnormality. Both cases illustrated the limitations of correctly characterizing some chromosomal abnormalities, including recombinant chromosomal abnormalities and isochromosome identification. In addition, 2 cases failed to reach a consensus for nomenclature reporting: 1 with an isochromosome and another with a duplication. Conclusions.— This 20-year review illustrates the high rate of competency and proficiency of cytogenetic laboratories in the correct identification of constitutional chromosome abnormalities.

Complex structural chromosome abnormalities such as chromoanagenesis have been reported in acute myeloid leukemia (AML). They are usually not well characterized by conventional genetic methods, and the characterization of chromoanagenesis structural abnormalities from short-read sequencing still presents challenges. Here, we characterized complex structural abnormalities involving chromosomes 2, 3, and 7 in an AML patient using an integrated approach including CRISPR/Cas9-mediated nanopore sequencing, mate pair sequencing (MPseq), and SNP microarray analysis along with cytogenetic methods. SNP microarray analysis revealed chromoanagenesis involving chromosomes 3 and 7, and a pseudotricentric chromosome 7 was revealed by cytogenetic methods. MPseq revealed 138 structural variants (SVs) as putative junctions of complex rearrangements involving chromosomes 2, 3, and 7, which led to 16 novel gene fusions and 33 truncated genes. Thirty CRISPR RNA (crRNA) sequences were designed to map 29 SVs, of which 27 (93.1%) were on-target based on CRISPR/Cas9 crRNA nanopore sequencing. In addition to simple SVs, complex SVs involving over two breakpoints were also revealed. Twenty-one SVs (77.8% of the on-target SVs) were also revealed by MPseq with shared SV breakpoints. Approximately three-quarters of breakpoints were located within genes, especially intronic regions, and one-quarter of breakpoints were intergenic. Alu and LINE repeat elements were frequent among breakpoints. Amplification of the chromosome 7 centromere was also detected by nanopore sequencing. Given the high amplification of the chromosome 7 centromere, extra chromosome 7 centromere sequences (tricentric), and more gains than losses of genomic material, chromoanasynthesis and chromothripsis may be responsible for forming this highly complex structural abnormality. We showed this combination approach’s value in characterizing complex structural abnormalities for clinical and research applications. Characterization of these complex structural chromosome abnormalities not only will help understand the molecular mechanisms responsible for the process of chromoanagenesis, but also may identify specific molecular targets and their impact on therapy and overall survival.

Abstract Despite the well-established role of recurrent gene fusions as oncogenic drivers, current practices for characterizing and interpreting gene fusion events in clinical testing and in biomedical literature are inconsistent. From the conceptual definition of gene fusions to the salient elements that characterize these alterations, a lack of community-driven standards for the curation of gene fusions has resulted in a disparate landscape of fusion representations and supporting tools. Consequently, the evidence-based clinical evaluation of gene fusions requires extensive expert review for accurate interpretation of observed gene fusions with respect to putative evidence from biomedical literature. Furthermore, the lack of these standards inhibits the interoperability of tools, resources, and pipelines - impeding data sharing and downstream utility.To address these challenges, a cross-consortia initiative between the Variant Interpretation for Cancer Consortium and ClinGen was formed to develop a standard operating procedure (SOP) for the curation of gene fusions. The SOP is under development by an international and diverse set of experts in the representation, detection, and clinical interpretation of gene fusions. Participating stakeholders across academic, government, and industry sectors showcased challenges and solutions, and participated in community surveys and discussions to define and develop the SOP for this diverse class of alterations.An initial result of this effort was the precise molecular definition of genomic events and features constituting gene fusions. We distinguish these from similar but distinct classes of structural alterations through clinically-relevant examples. Next, we discuss our findings on community practices around the description and evaluation of gene fusions. We provide our recommendations for characterization and representation of gene fusions from these practices, and compare these recommendations to existing variant representation standards and formats (e.g. HGVS variant nomenclature). We also discuss the concurrent application of formats for standardized human- and machine-readable representations of gene fusion events.We conclude with discussion of the salient elements to enable rapid, scalable, and consistent evaluation of fusions curated from the biomedical literature. Recommendations are provided for the standardized capture of these elements to enable both intuitive and precise characterization of this diverse class of alterations in clinical reporting and literature. In summary, we provide a clinical-practice driven framework and nomenclature for gene fusions, including recommendations for human readability, computational precision, and data integrity within the SOP. This work is a substantial advancement towards standardized communication, investigation, and sharing of gene fusion data across clinical and research domains and specialties. Citation Format: Alex H. Wagner, Ioannis S. Vlachos, Dmitriy Sonkin, Panieh Terraf, Chimene Kesserwan, Andrea Sboner, Thomas Coard, Christian Reich, Deborah I. Ritter, Peter Horak, Ying S. Zou, Anna Tanska, Aaron M. Berlin, Anna Lu, Daniel Cameron, Heather E. Williams, Wan-Hsin Lin, Gokce Toruner, Arpad Danos, Jason Saliba, Huiling Xu, Xinjie Xu, Georgina Ryland, Michele Ceccarelli, Liying Zhang, Sarah Rapisardo, Catherine Rehder, Xuelu Liu, Aparna Pallavajjala, Nicole Park, Laveniya Satgunaseelan, Kristy Lee, Jie Liu, Obi Griffith, Robert R. Freimuth, Albrecht Stenzinger, Linda B. Baughn, Michael Baudis, Jennifer Lee, Marilyn Li, Angshumoy Roy, Gordana Raca. A standard operating procedure for the curation of gene fusions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 449.

Abstract Objectives To demonstrate clinicopathologic features and evaluate the clonality of double PIK3CA alterations in colorectal cancers (CRCs). Methods Clonality was examined in 13 CRCs with double PIK3CA alterations (1.7% of CRCs or 9.6% of PIK3CA-mutated CRCs). Multiregional analyses were performed to confirm subclonal PIK3CA alterations. Results PIK3CA alterations were detected within exon 9 (51%), exon 20 (23%), exon 1 (15%), and exon 7 (6.0%). CRCs with exon 7 alterations showed a significantly higher incidence of double PIK3CA alterations. Most double PIK3CA alterations consisted of a hotpsot alteration and an uncommon alteration; they were often clonal and present within a single tumor population. Multiregional analyses of CRCs with predicted subclonal double-alterations revealed multiclonal CRCs with divergent PIK3CA variant status originating from a common APC- and KRAS-mutated founder lineage of adenoma. Conclusions The findings supported multiclonal CRCs resulting from parallel evolution during the progression from adenoma to adenocarcinoma within the mitogen-activated protein kinase pathway, as previously demonstrated, or the mammalian target of rapamycin pathway. Further studies are warranted to elucidate clinical significance and potential targeted therapy for CRC patients with double PIK3CA alterations and impacts on clinical decision-making in patients with multiclonal CRCs harboring divergent PIK3CA mutational status.

Abstract Background: In 2006 Lenalidomide received FDA approval for myelodysplasia (MDS) with interstitial deletion 5q [del(5q)] based on conventional cytogenetic (CC) results before and after treatment. In clinical practice, FISH studies of interphase nuclei with probes for EGR1 are widely used to detect del(5q), but it is not known whether this method has similar efficacy as CC. Thus, we compared CC and FISH results for various forms of del(5q). Methods: We selected 145 patients (pts) in our cytogenetic database with del(5q). These pts had various forms of del(5q) and were representative of our clinical practice. This series included 9 pts with MDS that were studied before and after treatment with Lenalidomide. CC studies were done using standard procedures to analyze 20 metaphases from bone marrow. FISH studies were done on the same specimens using stored left-over cells and standard procedures for EGR1 (5q31.2) and D5S23/D5S721 (5p15.2). The cutoff for del(5q) for FISH was <6.0% based on 200 nuclei. Results: Among 145 pts, 104 were referred for MDS, 9 acute myeloid leukemia, 9 lymphoproliferative disorders, 7 myeloproliferative disorders and 16 without clinical information. A total of 116 pts had breakpoints at del(5)(q13q33), 17 del(5)(q15q33), 8 del(5)(q11.2~q31q31~q35), 3 del(5)(q22q33) and 1 del(5)(q13q22). Del(5q) was detected in 144 pts by both CC and FISH. One pt had del(5)(q13q22) in 20/20 metaphases but was normal by FISH. Percent abnormal cells by FISH was lower in 135/145 pts compared to CC (mean difference 22.5 ± 19.6, range −42 to 98). For 9 pts with MDS, 29 specimens were collected before and after treatment with Lenalidomide: 7 achieved complete cytogenetic remission (four relapsed) and 2 showed a decrease in percent abnormal metaphases. Results of CC and FISH for these 9 pts were concordant for detection of del(5q) and trend of tumor burden due to treatment for 28/29 specimens. The discordant specimen was collected 222 days after treatment; results of CC were normal but FISH was abnormal in 19% of nuclei. Among the 29 specimens, percent abnormal cells by FISH was lower than CC in 27 (mean difference 13.9% ± 22.5, range −19.0 to 73.5). Each of the 9 treated pts had only del(5q) prior to treatment, and was detected by both FISH and CC. After treatment, FISH did not detect a separate cytogenetic clone involving deletion 20q without del(5q) in 2 pts nor did it identify development of other anomalies in 3 pts. Conclusions: Results of CC and FISH were mostly concordant, but differed in 4 respects. First, 1/145 pts was normal by FISH but had del(5q) by CC. This pt had unusual breakpoints that did not result in loss of EGR1. Second, percentage of cells with del(5q) was usually lower by FISH than CC. This observation is likely related to a different mitotic rate of cells with del(5q) versus normal cells. Third, 1 specimen was abnormal by FISH but normal by CC after treatment, but 2 subsequent specimens were concordant. This discrepancy was likely due to interference of mitosis of del(5q) cells and residual non-proliferating disease. Fourth, 2 treated pts developed a separate cytogenetic clone without del(5q) and 3 developed other anomalies that could not be detected by FISH. We believe FISH for EGR1 is useful in clinical practice, but not a substitute for CC.