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Clark KA, Paquette A, Tao K, Bell R, Boyle JL, Rosenthal J, Snow AK, Stark AW, Thompson BA, Unger J, Gertz J, Varley KE, Boucher KM, Goldgar DE, Foulkes WD, Thomas A, Tavtigian SV. Comprehensive evaluation and efficient classification of BRCA1 RING domain missense substitutions. Am J Hum Genet 2022; 109:1153-1174. [PMID: 35659930 PMCID: PMC9247830 DOI: 10.1016/j.ajhg.2022.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 05/09/2022] [Indexed: 11/21/2022] Open
Abstract
BRCA1 is a high-risk susceptibility gene for breast and ovarian cancer. Pathogenic protein-truncating variants are scattered across the open reading frame, but all known missense substitutions that are pathogenic because of missense dysfunction are located in either the amino-terminal RING domain or the carboxy-terminal BRCT domain. Heterodimerization of the BRCA1 and BARD1 RING domains is a molecularly defined obligate activity. Hence, we tested every BRCA1 RING domain missense substitution that can be created by a single nucleotide change for heterodimerization with BARD1 in a mammalian two-hybrid assay. Downstream of the laboratory assay, we addressed three additional challenges: assay calibration, validation thereof, and integration of the calibrated results with other available data, such as computational evidence and patient/population observational data to achieve clinically applicable classification. Overall, we found that 15%-20% of BRCA1 RING domain missense substitutions are pathogenic. Using a Bayesian point system for data integration and variant classification, we achieved clinical classification of 89% of observed missense substitutions. Moreover, among missense substitutions not present in the human observational data used here, we find an additional 45 with concordant computational and functional assay evidence in favor of pathogenicity plus 223 with concordant evidence in favor of benignity; these are particularly likely to be classified as likely pathogenic and likely benign, respectively, once human observational data become available.
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Affiliation(s)
- Kathleen A Clark
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA
| | - Andrew Paquette
- Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kayoko Tao
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA
| | - Russell Bell
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA
| | - Julie L Boyle
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA
| | - Judith Rosenthal
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA
| | - Angela K Snow
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA
| | - Alex W Stark
- Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Bryony A Thompson
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA
| | - Joshua Unger
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA
| | - Jason Gertz
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA; Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Katherine E Varley
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA; Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kenneth M Boucher
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA; Division of Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84108, USA
| | - David E Goldgar
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA; Department of Dermatology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - William D Foulkes
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC H3T 1E2, Canada; Research Institute McGill University Health Center, Montreal, QC H3T 1E2, Canada; Departments of Medicine, Human Genetics, and Oncology, McGill University, Montreal, QC H3T 1E2, Canada
| | - Alun Thomas
- Division of Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT 84108, USA
| | - Sean V Tavtigian
- Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT 84112, USA; Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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Byun S, Affolter KE, Snow AK, Curtin K, Cannon AR, Cannon-Albright LA, Thota R, Neklason DW. Differential methylation of G-protein coupled receptor signaling genes in gastrointestinal neuroendocrine tumors. Sci Rep 2021; 11:12303. [PMID: 34112938 PMCID: PMC8192774 DOI: 10.1038/s41598-021-91934-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 05/24/2021] [Indexed: 12/11/2022] Open
Abstract
Neuroendocrine tumors (NETs) of the small intestine undergo large chromosomal and methylation changes. The objective of this study was to identify methylation differences in NETs and consider how the differentially methylated genes may impact patient survival. Genome-wide methylation and chromosomal copy number variation (CNV) of NETs from the small intestine and appendix were measured. Tumors were divided into three molecular subtypes according to CNV results: chromosome 18 loss (18LOH), Multiple CNV, and No CNV. Comparison of 18LOH tumors with MultiCNV and NoCNV tumors identified 901 differentially methylated genes. Genes from the G-protein coupled receptor (GPCR) pathways are statistically overrepresented in the differentially methylated genes. One of the highlighted genes from the GPCR pathway is somatostatin (SST), a clinical target for NETs. Patient survival based on low versus high methylation in all samples identified four significant genes (p < 0.05) OR2S2, SMILR, RNU6-653P, and AC010543.1. Within the 18LOH molecular subtype tumors, survival differences were identified in high versus low methylation of 24 genes. The most significant is TRHR (p < 0.01), a GPCR with multiple FDA-approved drugs. By separating NETs into different molecular subtypes based on chromosomal changes, we find that multiple GPCRs and their ligands appear to be regulated through methylation and correlated with survival. These results suggest opportunities for better treatment strategies for NETs based on molecular features.
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Affiliation(s)
- Seyoun Byun
- Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, UT, 84112-5550, USA
- Department of Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, USA
| | - Kajsa E Affolter
- Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, UT, 84112-5550, USA
- Department of Pathology, University of Utah, Salt Lake City, USA
| | - Angela K Snow
- Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, UT, 84112-5550, USA
| | - Karen Curtin
- Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, UT, 84112-5550, USA
- Division of Epidemiology, Department of Internal Medicine, University of Utah, Salt Lake City, USA
| | - Austin R Cannon
- Division of General Surgery, Department of Surgery, University of Utah School of Medicine, Salt Lake City, USA
| | - Lisa A Cannon-Albright
- Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, UT, 84112-5550, USA
- Division of Epidemiology, Department of Internal Medicine, University of Utah, Salt Lake City, USA
| | - Ramya Thota
- Medical Oncology, Intermountain Healthcare, Salt Lake City, USA
| | - Deborah W Neklason
- Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, UT, 84112-5550, USA.
- Division of Epidemiology, Department of Internal Medicine, University of Utah, Salt Lake City, USA.
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3
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Thompson BA, Snow AK, Koptiuch C, Kohlmann WK, Mooney R, Johnson S, Huff CD, Yu Y, Teerlink CC, Feng BJ, Neklason DW, Cannon-Albright LA, Tavtigian SV. A novel ribosomal protein S20 variant in a family with unexplained colorectal cancer and polyposis. Clin Genet 2021; 97:943-944. [PMID: 32424863 DOI: 10.1111/cge.13757] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 02/21/2020] [Accepted: 02/23/2020] [Indexed: 01/23/2023]
Affiliation(s)
- Bryony A Thompson
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA.,Department of Pathology, Royal Melbourne Hospital, Melbourne, Australia.,Department of Clinical Pathology, University of Melbourne, Melbourne, Australia
| | - Angela K Snow
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
| | - Cathryn Koptiuch
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
| | - Wendy K Kohlmann
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
| | - Ryan Mooney
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
| | - Sara Johnson
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
| | - Chad D Huff
- Department of Epidemiology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Yao Yu
- Department of Epidemiology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Craig C Teerlink
- Division of Epidemiology, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Bing-Jian Feng
- Department of Dermatology, University of Utah, Salt Lake City, Utah, USA
| | - Deborah W Neklason
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA.,Division of Epidemiology, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Lisa A Cannon-Albright
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA.,Division of Epidemiology, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Research and Development Service, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, USA
| | - Sean V Tavtigian
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA.,Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, Utah, USA
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Cannon-Albright LA, Teerlink CC, Stevens J, Snow AK, Thompson BA, Bell R, Nguyen KN, Sargent NR, Kohlmann WK, Neklason DW, Tavtigian SV. FANCM c5791C>T stopgain mutation (rs144567652) is a familial colorectal cancer risk factor. Mol Genet Genomic Med 2020; 8:e1532. [PMID: 33118316 PMCID: PMC7767553 DOI: 10.1002/mgg3.1532] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/09/2020] [Accepted: 09/25/2020] [Indexed: 12/19/2022] Open
Abstract
Purpose While familial aggregation of colorectal cancer (CRC) is recognized, the majority of the germline predisposition factors remain unidentified, and many high‐risk CRC pedigrees remain unexplained by known risk variants. Fanconi Anemia genes have been recognized to be associated with cancer risk. Notably, FANCM (OMIM 609644) variants have been reported to confer risk for CRC and breast cancer. Methods Exome sequencing of CRC‐affected cousins in a set of 47 independent extended high‐risk CRC pedigrees identified a candidate set of rare, shared variants. Variants were tested for association with risk in 744 Utah CRC cases and 1525 controls, and for segregation with CRC in affected relatives. Results A FANCM stopgain variant was observed in two CRC‐affected cousin pairs, each from an independent Utah high‐risk pedigree, and yielded a nonsignificant, but elevated OR = 2.05 in a set of Utah cases and controls. Segregation of the variant to other related CRC‐affected cases was observed in the two extended pedigrees. Conclusion A rare stopgain variant in FANCM (rs144567652) that is recognized as a breast cancer predisposition variant, and that has previously been proposed, but not confirmed, as a CRC predisposition variant, is validated here as a risk factor for familial CRC.
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Affiliation(s)
- Lisa A Cannon-Albright
- Division of Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA.,Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Craig C Teerlink
- Division of Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Jeffrey Stevens
- Division of Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Angela K Snow
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Bryony A Thompson
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA.,Department of Pathology, Royal Melbourne Hospital, Melbourne, Australia
| | - Russell Bell
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Kim N Nguyen
- Division of Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Nykole R Sargent
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Wendy K Kohlmann
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Deborah W Neklason
- Division of Epidemiology, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA.,Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Sean V Tavtigian
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA.,Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
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Donovan LN, Kohlmann W, Snow AK, Neklason DW, Schiffman JD, Maese L. Germ Cell Mosaicism: A Rare Cause of Li-Fraumeni Recurrence Among Siblings. JCO Precis Oncol 2020; 4:PO.20.00064. [PMID: 32923893 PMCID: PMC7446446 DOI: 10.1200/po.20.00064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2020] [Indexed: 11/20/2022] Open
Affiliation(s)
| | - Wendy Kohlmann
- University of Utah Huntsman Cancer Institute, Salt Lake City, UT
| | - Angela K. Snow
- University of Utah Huntsman Cancer Institute, Salt Lake City, UT
| | - Deborah W. Neklason
- University of Utah Huntsman Cancer Institute, Salt Lake City, UT
- Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT
| | - Joshua D. Schiffman
- University of Utah Huntsman Cancer Institute, Salt Lake City, UT
- University of Utah Department of Pediatrics, Salt Lake City, UT
| | - Luke Maese
- University of Utah Huntsman Cancer Institute, Salt Lake City, UT
- University of Utah Department of Pediatrics, Salt Lake City, UT
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Chavez DR, Snow AK, Smith JR, Stanfield GM. Soma-germ line interactions and a role for muscle in the regulation of C. elegans sperm motility. Development 2018; 145:dev.167734. [PMID: 30470702 DOI: 10.1242/dev.167734] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 11/12/2018] [Indexed: 12/13/2022]
Abstract
The development of highly differentiated sperm cells that are specialized for navigating to and fusing with an oocyte is essential for sexual reproduction. As a major part of differentiation, sperm undergo extensive post-meiotic maturation en route to the oocyte. This is regulated largely by soma-derived cues. In Caenorhabditis elegans, this process is called sperm activation, and it transforms immotile spermatids into migratory fertilization-competent cells. Here, we show that the negative regulator of sperm activation, SWM-1, is produced in an unexpected cell type: body wall muscle. SWM-1 is secreted into the body cavity and enters the gonad; there, it is present with its likely target, TRY-5, a spermiogenesis activator. We show that, in addition to SWM-1, the somatic gonad and body fluid can exchange other factors, suggesting that soma-germ line transfer could affect other reproductive processes. In addition, we show that SWM-1 may have a separate role in the sperm migratory environment, to which it is contributed by both males and hermaphrodites. These findings reveal that late stages in gamete differentiation can be regulated at the whole-organism level by broadly secreted factors.This article has an associated 'The people behind the papers' interview.
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Affiliation(s)
- Daniela R Chavez
- Department of Human Genetics, University of Utah, 15 North 2030 East, Salt Lake City, UT 84112, USA.,Smithsonian Conservation Biology Institute, National Zoological Park, 3001 Connecticut Ave. NW, Washington, DC 20008, USA
| | - Angela K Snow
- Department of Human Genetics, University of Utah, 15 North 2030 East, Salt Lake City, UT 84112, USA
| | - Joseph R Smith
- Department of Human Genetics, University of Utah, 15 North 2030 East, Salt Lake City, UT 84112, USA
| | - Gillian M Stanfield
- Department of Human Genetics, University of Utah, 15 North 2030 East, Salt Lake City, UT 84112, USA
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Delker DA, Wood AC, Snow AK, Samadder NJ, Samowitz WS, Affolter KE, Boucher KM, Pappas LM, Stijleman IJ, Kanth P, Byrne KR, Burt RW, Bernard PS, Neklason DW. Chemoprevention with Cyclooxygenase and Epidermal Growth Factor Receptor Inhibitors in Familial Adenomatous Polyposis Patients: mRNA Signatures of Duodenal Neoplasia. Cancer Prev Res (Phila) 2018; 11:4-15. [PMID: 29109117 PMCID: PMC5754246 DOI: 10.1158/1940-6207.capr-17-0130] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 08/31/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022]
Abstract
To identify gene expression biomarkers and pathways targeted by sulindac and erlotinib given in a chemoprevention trial with a significant decrease in duodenal polyp burden at 6 months (P < 0.001) in familial adenomatous polyposis (FAP) patients, we biopsied normal and polyp duodenal tissues from patients on drug versus placebo and analyzed the RNA expression. RNA sequencing was performed on biopsies from the duodenum of FAP patients obtained at baseline and 6-month endpoint endoscopy. Ten FAP patients on placebo and 10 on sulindac and erlotinib were selected for analysis. Purity of biopsied polyp tissue was calculated from RNA expression data. RNAs differentially expressed between endpoint polyp and paired baseline normal were determined for each group and mapped to biological pathways. Key genes in candidate pathways were further validated by quantitative RT-PCR. RNA expression analyses of endpoint polyp compared with paired baseline normal for patients on placebo and drug show that pathways activated in polyp growth and proliferation are blocked by this drug combination. Directly comparing polyp gene expression between patients on drug and placebo also identified innate immune response genes (IL12 and IFNγ) preferentially expressed in patients on drug. Gene expression analyses from tissue obtained at endpoint of the trial demonstrated inhibition of the cancer pathways COX2/PGE2, EGFR, and WNT. These findings provide molecular evidence that the drug combination of sulindac and erlotinib reached the intended tissue and was on target for the predicted pathways. Furthermore, activation of innate immune pathways from patients on drug may have contributed to polyp regression. Cancer Prev Res; 11(1); 4-15. ©2017 AACRSee related editorial by Shureiqi, p. 1.
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Affiliation(s)
- Don A Delker
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Austin C Wood
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Angela K Snow
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - N Jewel Samadder
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Wade S Samowitz
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
- Department of Pathology, University of Utah, Salt Lake City, Utah
| | - Kajsa E Affolter
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
- Department of Pathology, University of Utah, Salt Lake City, Utah
| | - Kenneth M Boucher
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Lisa M Pappas
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Inge J Stijleman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Priyanka Kanth
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Kathryn R Byrne
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Randall W Burt
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Philip S Bernard
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
- Department of Pathology, University of Utah, Salt Lake City, Utah
| | - Deborah W Neklason
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah.
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
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8
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Snow AK, Tuohy TMF, Sargent NR, Smith LJ, Burt RW, Neklason DW. APC promoter 1B deletion in seven American families with familial adenomatous polyposis. Clin Genet 2014; 88:360-5. [PMID: 25243319 DOI: 10.1111/cge.12503] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 12/27/2022]
Abstract
Familial adenomatous polyposis (FAP) is a colorectal cancer predisposition syndrome caused by mutations in the adenomatous polyposis coli (APC) gene. Clinical genetic testing fails to identify disease causing mutations in up to 20% of clinically apparent FAP cases. Following the inclusion of multiplex ligation-dependent probe amplification (MLPA) probes specific for APC promoter 1B, seven probands were identified with a deletion of promoter 1B. Using haplotype analysis spanning the APC locus, the seven families appear to be identical by descent from a common founder. The clinical phenotype of 19 mutation carriers is classical FAP with colectomy at an average age of 24. The majority of cases had a large number of duodenal and gastric polyps. Measurements of allele-specific expression of APC mRNA using TaqMan assay confirmed that relative expression in the allele containing the promoter 1B deletion was reduced 42-98%, depending on tissue type. This study confirms the importance of APC promoter deletions as a cause of FAP and identifies a founder mutation in FAP patients from the United States.
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Affiliation(s)
| | | | | | | | - R W Burt
- Huntsman Cancer Institute.,Division of Gastroenterology
| | - D W Neklason
- Huntsman Cancer Institute.,Division of Genetic Epidemiology, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
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