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Biskup E, Lopacinska-Jørgensen J, Vestergaard LK, Høgdall E. Validating reference-based algorithms to determine cell-type heterogeneity in ovarian cancer DNA methylation studies. Sci Rep 2024; 14:11048. [PMID: 38745057 PMCID: PMC11094148 DOI: 10.1038/s41598-024-61857-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 05/10/2024] [Indexed: 05/16/2024] Open
Abstract
Information about cell composition in tissue samples is crucial for biomarker discovery and prognosis. Specifically, cancer tissue samples present challenges in deconvolution studies due to mutations and genetic rearrangements. Here, we optimized a robust, DNA methylation-based protocol, to be used for deconvolution of ovarian cancer samples. We compared several state-of-the-art methods (HEpiDISH, MethylCIBERSORT and ARIC) and validated the proposed protocol in an in-silico mixture and in an external dataset containing samples from ovarian cancer patients and controls. The deconvolution protocol we eventually implemented is based on MethylCIBERSORT. Comparing deconvolution methods, we paid close attention to the role of a reference panel. We postulate that a possibly high number of samples (in our case: 247) should be used when building a reference panel to ensure robustness and to compensate for biological and technical variation between samples. Subsequently, we tested the performance of the validated protocol in our own study cohort, consisting of 72 patients with malignant and benign ovarian disease as well as in five external cohorts. In conclusion, we refined and validated a reference-based algorithm to determine cell type composition of ovarian cancer tissue samples to be used in cancer biology studies in larger cohorts.
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Affiliation(s)
- Edyta Biskup
- Department of Pathology, Copenhagen University Hospital, Herlev, Denmark.
| | | | | | - Estrid Høgdall
- Department of Pathology, Copenhagen University Hospital, Herlev, Denmark
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2
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Maié T, Schmidt M, Erz M, Wagner W, G Costa I. CimpleG: finding simple CpG methylation signatures. Genome Biol 2023; 24:161. [PMID: 37430364 DOI: 10.1186/s13059-023-03000-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 06/28/2023] [Indexed: 07/12/2023] Open
Abstract
DNA methylation signatures are usually based on multivariate approaches that require hundreds of sites for predictions. Here, we propose a computational framework named CimpleG for the detection of small CpG methylation signatures used for cell-type classification and deconvolution. We show that CimpleG is both time efficient and performs as well as top performing methods for cell-type classification of blood cells and other somatic cells, while basing its prediction on a single DNA methylation site per cell type. Altogether, CimpleG provides a complete computational framework for the delineation of DNAm signatures and cellular deconvolution.
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Affiliation(s)
- Tiago Maié
- Institute for Computational Genomics, Joint Research Center for Computational Biomedicine, RWTH Aachen University Medical School, Pauwelsstr. 19, Aachen, 52074, NRW, Germany.
| | - Marco Schmidt
- Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 19, Aachen, 52074, NRW, Germany
- Institute for Stem Cell Biology, RWTH Aachen University Medical School, Pauwelsstr. 19, Aachen, 52074, NRW, Germany
| | - Myriam Erz
- Institute for Computational Genomics, Joint Research Center for Computational Biomedicine, RWTH Aachen University Medical School, Pauwelsstr. 19, Aachen, 52074, NRW, Germany
| | - Wolfgang Wagner
- Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 19, Aachen, 52074, NRW, Germany
- Institute for Stem Cell Biology, RWTH Aachen University Medical School, Pauwelsstr. 19, Aachen, 52074, NRW, Germany
| | - Ivan G Costa
- Institute for Computational Genomics, Joint Research Center for Computational Biomedicine, RWTH Aachen University Medical School, Pauwelsstr. 19, Aachen, 52074, NRW, Germany.
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3
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Miheecheva N, Postovalova E, Lyu Y, Ramachandran A, Bagaev A, Svekolkin V, Galkin I, Zyrin V, Maximov V, Lozinsky Y, Isaev S, Ovcharov P, Shamsutdinova D, Cheng EH, Nomie K, Brown JH, Tsiper M, Ataullakhanov R, Fowler N, Hsieh JJ. Multiregional single-cell proteogenomic analysis of ccRCC reveals cytokine drivers of intratumor spatial heterogeneity. Cell Rep 2022; 40:111180. [PMID: 35977503 DOI: 10.1016/j.celrep.2022.111180] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 06/23/2022] [Accepted: 07/19/2022] [Indexed: 11/17/2022] Open
Abstract
Intratumor heterogeneity (ITH) represents a major challenge for anticancer therapies. An integrated, multidimensional, multiregional approach dissecting ITH of the clear cell renal cell carcinoma (ccRCC) tumor microenvironment (TME) is employed at the single-cell level with mass cytometry (CyTOF), multiplex immunofluorescence (MxIF), and single-nucleus RNA sequencing (snRNA-seq) and at the bulk level with whole-exome sequencing (WES), RNA-seq, and methylation profiling. Multiregional analyses reveal unexpected conservation of immune composition within each individual patient, with profound differences among patients, presenting patient-specific tumor immune microenvironment signatures despite underlying genetic heterogeneity from clonal evolution. Spatial proteogenomic TME analysis using MxIF identifies 14 distinct cellular neighborhoods and, conversely, demonstrated architectural heterogeneity among different tumor regions. Tumor-expressed cytokines are identified as key determinants of the TME and correlate with clinical outcome. Overall, this work signifies that spatial ITH occurs in ccRCC, which may drive clinical heterogeneity and warrants further interrogation to improve patient outcomes.
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Affiliation(s)
- Natalia Miheecheva
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Ekaterina Postovalova
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Yang Lyu
- Molecular Oncology, Division of Oncology, Department of Medicine, Washington University, St. Louis, MO 63110, USA
| | - Akshaya Ramachandran
- Molecular Oncology, Division of Oncology, Department of Medicine, Washington University, St. Louis, MO 63110, USA
| | - Alexander Bagaev
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Viktor Svekolkin
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Ilia Galkin
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Vladimir Zyrin
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Vladislav Maximov
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Yaroslav Lozinsky
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Sergey Isaev
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Pavel Ovcharov
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Diana Shamsutdinova
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Emily H Cheng
- Human Oncology and Pathogenesis Program and Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Krystle Nomie
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Jessica H Brown
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Maria Tsiper
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Ravshan Ataullakhanov
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA
| | - Nathan Fowler
- BostonGene Corporation, University Office Park III, 95 Sawyer Road, Waltham, MA 02453, USA.
| | - James J Hsieh
- Molecular Oncology, Division of Oncology, Department of Medicine, Washington University, St. Louis, MO 63110, USA.
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4
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Hilser JR, Hartiala JA, Sriprasert I, Kono N, Cai Z, Karim R, DeYoung J, Mack WJ, Hodis HN, Allayee H. Effect of menopausal hormone therapy on methylation levels in early and late postmenopausal women. Clin Epigenetics 2022; 14:90. [PMID: 35850911 PMCID: PMC9295504 DOI: 10.1186/s13148-022-01311-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/28/2022] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Cardiovascular disease (CVD) remains the leading cause of death among postmenopausal women but standard primary prevention strategies in women are not as effective as in men. By comparison, the Early versus Late Intervention Trial with Estradiol (ELITE) study demonstrated that hormone therapy (HT) was associated with significant reduction in atherosclerosis progression in women who were within six years of menopause compared to those who were 10 or more years from menopause. These findings are consistent with other studies showing significant reductions in all-cause mortality and CVD with HT, particularly when initiated in women younger than 60 years of age or within 10 years since menopause. To explore the biological mechanisms underlying the age-related atheroprotective effects of HT, we investigated changes in methylation of blood cells of postmenopausal women who participated in ELITE. RESULTS We first validated the epigenetic data generated from blood leukocytes of ELITE participants by replicating previously known associations between smoking and methylation levels at previously identified CpG sites, such as cg05575921 at the AHRR locus. An epigenome-wide association study (EWAS) evaluating changes in methylation through interactions with time-since-menopause and HT revealed two significantly associated CpG sites on chromosomes 12 (cg19552895; p = 1.1 × 10-9) and 19 (cg18515510; p = 2.4 × 10-8). Specifically, HT resulted in modest, but significant, increases in methylation levels at both CpGs but only in women who were 10 or more years since menopause and randomized to HT. Changes in carotid artery intima-media thickness (CIMT) from baseline to 36 months after HT were not significantly correlated with changes in methylation levels at either cg19552895 or cg18515510. Evaluation of other previously identified CpG sites at which methylation levels in either blood or vascular tissue were associated with atherosclerosis also did not reveal any differences in methylation as a function of HT and time-since-menopause or with changes in CIMT. CONCLUSIONS We identified specific methylation differences in blood in response to HT among women who were 10 or more years since menopause. The functional consequence of these change with respect to atherosclerosis progression and protective effects of HT remains to be determined and will require additional studies.
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Affiliation(s)
- James R. Hilser
- grid.42505.360000 0001 2156 6853Departments of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC202, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Departments of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA
| | - Jaana A. Hartiala
- grid.42505.360000 0001 2156 6853Departments of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC202, Los Angeles, CA 90033 USA
| | - Intira Sriprasert
- grid.42505.360000 0001 2156 6853Departments of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA
| | - Naoko Kono
- grid.42505.360000 0001 2156 6853Departments of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC202, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Atherosclerosis Research Unit, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA
| | - Zhiheng Cai
- grid.42505.360000 0001 2156 6853Departments of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC202, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Departments of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA
| | - Roksana Karim
- grid.42505.360000 0001 2156 6853Departments of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC202, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Atherosclerosis Research Unit, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA
| | - Joseph DeYoung
- grid.19006.3e0000 0000 9632 6718Department of Psychiatry and Biobehavioral Sciences, Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine of UCLA, Los Angeles, CA 90095 USA
| | - Wendy J. Mack
- grid.42505.360000 0001 2156 6853Departments of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC202, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Atherosclerosis Research Unit, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA
| | - Howard N. Hodis
- grid.42505.360000 0001 2156 6853Departments of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC202, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Departments of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Atherosclerosis Research Unit, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA
| | - Hooman Allayee
- grid.42505.360000 0001 2156 6853Departments of Population and Public Health Sciences, Keck School of Medicine, University of Southern California, 2250 Alcazar Street, CSC202, Los Angeles, CA 90033 USA ,grid.42505.360000 0001 2156 6853Departments of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033 USA
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Singh O, Pratt D, Aldape K. Immune cell deconvolution of bulk DNA methylation data reveals an association with methylation class, key somatic alterations, and cell state in glial/glioneuronal tumors. Acta Neuropathol Commun 2021; 9:148. [PMID: 34496929 PMCID: PMC8425010 DOI: 10.1186/s40478-021-01249-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 08/23/2021] [Indexed: 02/08/2023] Open
Abstract
It is recognized that the tumor microenvironment (TME) plays a critical role in the biology of cancer. To better understand the role of immune cell components in CNS tumors, we applied a deconvolution approach to bulk DNA methylation array data in a large set of newly profiled samples (n = 741) as well as samples from external data sources (n = 3311) of methylation-defined glial and glioneuronal tumors. Using the cell-type proportion data as input, we used dimensionality reduction to visualize sample-wise patterns that emerge from the cell type proportion estimations. In IDH-wildtype glioblastomas (n = 2,072), we identified distinct tumor clusters based on immune cell proportion and demonstrated an association with oncogenic alterations such as EGFR amplification and CDKN2A/B homozygous deletion. We also investigated the immune cluster-specific distribution of four malignant cellular states (AC-like, OPC-like, MES-like and NPC-like) in the IDH-wildtype cohort. We identified two major immune-based subgroups of IDH-mutant gliomas, which largely aligned with 1p/19q co-deletion status. Non-codeleted gliomas showed distinct proportions of a key genomic aberration (CDKN2A/B loss) among immune cell-based groups. We also observed significant positive correlations between monocyte proportion and expression of PD-L1 and PD-L2 (R = 0.54 and 0.68, respectively). Overall, the findings highlight specific roles of the TME in biology and classification of CNS tumors, where specific immune cell admixtures correlate with tumor types and genomic alterations.
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Affiliation(s)
- Omkar Singh
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Drew Pratt
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Department of Pathology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Kenneth Aldape
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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6
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Schmidt M, Maié T, Dahl E, Costa IG, Wagner W. Deconvolution of cellular subsets in human tissue based on targeted DNA methylation analysis at individual CpG sites. BMC Biol 2020; 18:178. [PMID: 33234153 PMCID: PMC7687708 DOI: 10.1186/s12915-020-00910-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/28/2020] [Indexed: 12/12/2022] Open
Abstract
Background The complex composition of different cell types within a tissue can be estimated by deconvolution of bulk gene expression profiles or with various single-cell sequencing approaches. Alternatively, DNA methylation (DNAm) profiles have been used to establish an atlas for multiple human tissues and cell types. DNAm is particularly suitable for deconvolution of cell types because each CG dinucleotide (CpG site) has only two states per DNA strand—methylated or non-methylated—and these epigenetic modifications are very consistent during cellular differentiation. So far, deconvolution of DNAm profiles implies complex signatures of many CpGs that are often measured by genome-wide analysis with Illumina BeadChip microarrays. In this study, we investigated if the characterization of cell types in tissue is also feasible with individual cell type-specific CpG sites, which can be addressed by targeted analysis, such as pyrosequencing. Results We compiled and curated 579 Illumina 450k BeadChip DNAm profiles of 14 different non-malignant human cell types. A training and validation strategy was applied to identify and test for cell type-specific CpGs. We initially focused on estimating the relative amount of fibroblasts using two CpGs that were either hypermethylated or hypomethylated in fibroblasts. The combination of these two DNAm levels into a “FibroScore” correlated with the state of fibrosis and was associated with overall survival in various types of cancer. Furthermore, we identified hypomethylated CpGs for leukocytes, endothelial cells, epithelial cells, hepatocytes, glia, neurons, fibroblasts, and induced pluripotent stem cells. The accuracy of this eight CpG signature was tested in additional BeadChip datasets of defined cell mixtures and the results were comparable to previously published signatures based on several thousand CpGs. Finally, we established and validated pyrosequencing assays for the relevant CpGs that can be utilized for classification and deconvolution of cell types. Conclusion This proof of concept study demonstrates that DNAm analysis at individual CpGs reflects the cellular composition of cellular mixtures and different tissues. Targeted analysis of these genomic regions facilitates robust methods for application in basic research and clinical settings.
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Affiliation(s)
- Marco Schmidt
- Helmholtz-Institute for Biomedical Engineering, Stem Cell Biology and Cellular Engineering, RWTH Aachen University Medical School, 52074, Aachen, Germany.,Institute for Biomedical Engineering - Cell Biology, University Hospital of RWTH Aachen, 52074, Aachen, Germany
| | - Tiago Maié
- Institute for Computational Genomics, Joint Research Center for Computational Biomedicine, RWTH Aachen University Medical School, 52074, Aachen, Germany
| | - Edgar Dahl
- RWTH centralized Biomaterial Bank (RWTH cBMB), Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Ivan G Costa
- Institute for Computational Genomics, Joint Research Center for Computational Biomedicine, RWTH Aachen University Medical School, 52074, Aachen, Germany
| | - Wolfgang Wagner
- Helmholtz-Institute for Biomedical Engineering, Stem Cell Biology and Cellular Engineering, RWTH Aachen University Medical School, 52074, Aachen, Germany. .,Institute for Biomedical Engineering - Cell Biology, University Hospital of RWTH Aachen, 52074, Aachen, Germany.
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7
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Ciolfi A, Aref-Eshghi E, Pizzi S, Pedace L, Miele E, Kerkhof J, Flex E, Martinelli S, Radio FC, Ruivenkamp CAL, Santen GWE, Bijlsma E, Barge-Schaapveld D, Ounap K, Siu VM, Kooy RF, Dallapiccola B, Sadikovic B, Tartaglia M. Frameshift mutations at the C-terminus of HIST1H1E result in a specific DNA hypomethylation signature. Clin Epigenetics 2020; 12:7. [PMID: 31910894 PMCID: PMC6947958 DOI: 10.1186/s13148-019-0804-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/26/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND We previously associated HIST1H1E mutations causing Rahman syndrome with a specific genome-wide methylation pattern. RESULTS Methylome analysis from peripheral blood samples of six affected subjects led us to identify a specific hypomethylated profile. This "episignature" was enriched for genes involved in neuronal system development and function. A computational classifier yielded full sensitivity and specificity in detecting subjects with Rahman syndrome. Applying this model to a cohort of undiagnosed probands allowed us to reach diagnosis in one subject. CONCLUSIONS We demonstrate an epigenetic signature in subjects with Rahman syndrome that can be used to reach molecular diagnosis.
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Affiliation(s)
- Andrea Ciolfi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146, Rome, Italy
| | - Erfan Aref-Eshghi
- Department of Pathology and Laboratory Medicine, Western University, London, N6A 5C1, Canada.,Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, N6A 5W9, Canada
| | - Simone Pizzi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146, Rome, Italy
| | - Lucia Pedace
- Department of Pediatric Onco-Hematology and Cell and Gene Therapy, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146, Rome, Italy
| | - Evelina Miele
- Department of Pediatric Onco-Hematology and Cell and Gene Therapy, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146, Rome, Italy
| | - Jennifer Kerkhof
- Department of Pathology and Laboratory Medicine, Western University, London, N6A 5C1, Canada.,Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, N6A 5W9, Canada
| | - Elisabetta Flex
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Simone Martinelli
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Francesca Clementina Radio
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146, Rome, Italy
| | - Claudia A L Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, 2300, The Netherlands
| | - Gijs W E Santen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, 2300, The Netherlands
| | - Emilia Bijlsma
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, 2300, The Netherlands
| | - Daniela Barge-Schaapveld
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, 2300, The Netherlands
| | - Katrin Ounap
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, 50406, Tartu, Estonia.,Institute of Clinical Medicine, University of Tartu, 50406, Tartu, Estonia
| | - Victoria Mok Siu
- Medical Genetics Program of Southwestern Ontario, London Health Sciences Centre, London, ON, N6A 5W9, Canada
| | - R Frank Kooy
- Department of Medical Genetics, University of Antwerp, 2650, Antwerp, Belgium
| | - Bruno Dallapiccola
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146, Rome, Italy
| | - Bekim Sadikovic
- Department of Pathology and Laboratory Medicine, Western University, London, N6A 5C1, Canada. .,Molecular Genetics Laboratory, Molecular Diagnostics Division, London Health Sciences Centre, London, N6A 5W9, Canada.
| | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146, Rome, Italy.
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