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Truty R, Rojahn S, Ouyang K, Kautzer C, Kennemer M, Pineda-Alvarez D, Johnson B, Stafford A, Basel-Salmon L, Saitta S, Slavotinek A, Chandrasekharappa SC, Suarez CJ, Burnett L, Nussbaum RL, Aradhya S. Patterns of mosaicism for sequence and copy-number variants discovered through clinical deep sequencing of disease-related genes in one million individuals. Am J Hum Genet 2023; 110:551-564. [PMID: 36933558 PMCID: PMC10119133 DOI: 10.1016/j.ajhg.2023.02.013] [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: 09/22/2022] [Accepted: 02/23/2023] [Indexed: 03/19/2023] Open
Abstract
DNA variants that arise after conception can show mosaicism, varying in presence and extent among tissues. Mosaic variants have been reported in Mendelian diseases, but further investigation is necessary to broadly understand their incidence, transmission, and clinical impact. A mosaic pathogenic variant in a disease-related gene may cause an atypical phenotype in terms of severity, clinical features, or timing of disease onset. Using high-depth sequencing, we studied results from one million unrelated individuals referred for genetic testing for almost 1,900 disease-related genes. We observed 5,939 mosaic sequence or intragenic copy number variants distributed across 509 genes in nearly 5,700 individuals, constituting approximately 2% of molecular diagnoses in the cohort. Cancer-related genes had the most mosaic variants and showed age-specific enrichment, in part reflecting clonal hematopoiesis in older individuals. We also observed many mosaic variants in genes related to early-onset conditions. Additional mosaic variants were observed in genes analyzed for reproductive carrier screening or associated with dominant disorders with low penetrance, posing challenges for interpreting their clinical significance. When we controlled for the potential involvement of clonal hematopoiesis, most mosaic variants were enriched in younger individuals and were present at higher levels than in older individuals. Furthermore, individuals with mosaicism showed later disease onset or milder phenotypes than individuals with non-mosaic variants in the same genes. Collectively, the large compendium of variants, disease correlations, and age-specific results identified in this study expand our understanding of the implications of mosaic DNA variation for diagnosis and genetic counseling.
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Affiliation(s)
- Rebecca Truty
- Invitae, 1400 16th Street, San Francisco, CA 94103, USA
| | - Susan Rojahn
- Invitae, 1400 16th Street, San Francisco, CA 94103, USA
| | - Karen Ouyang
- Invitae, 1400 16th Street, San Francisco, CA 94103, USA
| | | | | | | | - Britt Johnson
- Invitae, 1400 16th Street, San Francisco, CA 94103, USA
| | | | - Lina Basel-Salmon
- Rabin Medical Center-Beilinson Hospital and Schneider Children's Medical Center of Israel, Petach Tikva, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Felsenstein Medical Research Center, Petach Tikva, Israel
| | - Sulagna Saitta
- Division of Clinical Genetics, Departments of Pediatrics and Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Anne Slavotinek
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Settara C Chandrasekharappa
- Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Carlos Jose Suarez
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94301, USA
| | | | - Robert L Nussbaum
- Invitae, 1400 16th Street, San Francisco, CA 94103, USA; School of Medicine, University of California - San Francisco, San Francisco, CA, USA
| | - Swaroop Aradhya
- Invitae, 1400 16th Street, San Francisco, CA 94103, USA; Department of Pathology, Stanford University School of Medicine, Stanford, CA 94301, USA.
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Mussa A, Turchiano A, Cardaropoli S, Coppo P, Pantaleo A, Bagnulo R, Ranieri C, Iacoviello M, Garganese A, Stella A, Vallero SG, Bertin D, Santoro F, Carli D, Ferrero GB, Resta N. Lateralized overgrowth with vascular malformation caused by a somatic PTPN11 pathogenic variant: another piece added to the puzzle of mosaic RASopathies. Genes Chromosomes Cancer 2022; 61:689-695. [PMID: 35778969 PMCID: PMC9542063 DOI: 10.1002/gcc.23086] [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: 03/28/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 11/23/2022] Open
Abstract
Lateralized/segmental overgrowth disorders (LOs) encompass a heterogeneous group of congenital conditions with excessive body tissue growth. Documented molecular alterations in LOs mostly consist of somatic variants in genes of the PI3KCA/AKT/mTOR pathway or of chromosome band 11p15.5 imprinted region anomalies. In some cases, somatic pathogenic variants in genes of the RAS/MAPK pathway have been reported. We present the first case of a somatic pathogenic variant (T507K) in PTPN11 causing a LO phenotype characterized by severe lateralized overgrowth, vascular proliferation, and cerebral astrocytoma. The T507K variant was detected in DNA from overgrown tissue in a leg with capillary malformation. The astrocytoma tissue showed a higher PTPN11 variant allele frequency. A pathogenic variant in FGFR1 was also found in tumor tissue, representing a second hit on the RAS/MAPK pathway. These findings indicate that RAS/MAPK cascade overactivation can cause mosaic overgrowth phenotypes resembling PIK3CA‐related overgrowth disorders (PROS) with cancer predisposition and are consistent with the hypothesis that RAS/MAPK hyperactivation can be involved in the pathogenesis of astrocytoma. This observation raises the issue of cancer predisposition in patients with RAS/MAPK pathway gene variants and expands genotype spectrum of LOs and the treatment options for similar cases through inhibition of the RAS/MAPK oversignaling.
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Affiliation(s)
- Alessandro Mussa
- Department of Public Health and Pediatric Sciences, University of Torino, Torino, Italy.,Pediatric Clinical Genetics Unit, Regina Margherita Children's Hospital, Città della Salute e della Scienza, Torino, Italy
| | - Antonella Turchiano
- Department of Biomedical Sciences and Human Oncology (DIMO), Division of Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Simona Cardaropoli
- Department of Public Health and Pediatric Sciences, University of Torino, Torino, Italy
| | - Paola Coppo
- Pediatric Dermatology, Regina Margherita Children's Hospital, Città della Salute e della Scienza di Torino, Torino, Italy
| | - Antonino Pantaleo
- Department of Biomedical Sciences and Human Oncology (DIMO), Division of Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Rosanna Bagnulo
- Department of Biomedical Sciences and Human Oncology (DIMO), Division of Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Carlotta Ranieri
- Department of Biomedical Sciences and Human Oncology (DIMO), Division of Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Matteo Iacoviello
- Department of Biomedical Sciences and Human Oncology (DIMO), Division of Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Antonella Garganese
- Unit of Medical Genetics, Ospedale Consorziale Policlinico di Bari, Bari, Italy
| | - Alessandro Stella
- Department of Biomedical Sciences and Human Oncology (DIMO), Division of Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
| | - Stefano Gabriele Vallero
- Pediatric Onco-Hematology, Regina Margherita Children's Hospital, Città della Salute e della Scienza di Torino, Torino, Italy
| | - Daniele Bertin
- Pediatric Onco-Hematology, Regina Margherita Children's Hospital, Città della Salute e della Scienza di Torino, Torino, Italy
| | - Federica Santoro
- Pathology Unit, Department of Medical Sciences, University of Torino, Torino, Italy
| | - Diana Carli
- Department of Public Health and Pediatric Sciences, University of Torino, Torino, Italy.,Pediatric Onco-Hematology, Regina Margherita Children's Hospital, Città della Salute e della Scienza di Torino, Torino, Italy
| | | | - Nicoletta Resta
- Department of Biomedical Sciences and Human Oncology (DIMO), Division of Medical Genetics, University of Bari "Aldo Moro", Bari, Italy
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