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Kim SW, Kim B, Kim Y, Lee KA. Re-evaluation of a Fibrillin-1 Gene Variant of Uncertain Significance Using the ClinGen Guidelines. Ann Lab Med 2024; 44:271-278. [PMID: 37840311 PMCID: PMC10813823 DOI: 10.3343/alm.2023.0152] [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: 04/10/2023] [Revised: 07/25/2023] [Accepted: 09/12/2023] [Indexed: 10/17/2023] Open
Abstract
Background Marfan syndrome (MFS) is caused by fibrillin-1 gene (FBN1) variants. Mutational hotspots and/or well-established critical functional domains of FBN1 include cysteine residues, calcium-binding consensus sequences, and amino acids related to interdomain packaging. Previous guidelines for variant interpretation do not reflect the features of genes or related diseases. Using the Clinical Genome Resource (ClinGen) FBN1 variant curation expert panel (VCEP), we re-evaluated FBN1 germline variants reported as variants of uncertain significance (VUSs). Methods We re-evaluated 26 VUSs in FBN1 reported in 161 patients with MFS. We checked the variants in the Human Genome Mutation Database, ClinVar, and VarSome databases and assessed their allele frequencies using the gnomAD database. Patients' clinical information was reviewed. Results Four missense variants affecting cysteines (c.460T>C, c.1006T>C, c.5330G>C, and c.8020T>C) were reclassified as likely pathogenic and were assigned PM1_strong or PM1. Two intronic variants were reclassified as benign by granting BA1 (stand-alone). Four missense variants were reclassified as likely benign. BP5 criteria were applied in cases with an alternate molecular basis for disease, one of which (c.7231G>A) was discovered alongside a pathogenic de novo COL3A1 variant (c.1988G>T, p.Gly633Val). Conclusions Considering the high penetrance of FBN1 variants and clinical variability of MFS, the detection of pathogenic variants is important. The ClinGen FBN1 VCEP encompasses mutational hotspots and/or well-established critical functional domains and adjusts the criteria specifically for MFS; therefore, it is beneficial not only for identifying pathogenic FBN1 variants but also for distinguishing these variants from those that cause other connective tissue disorders with overlapping clinical features.
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Affiliation(s)
- Seo Wan Kim
- Department of Laboratory Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Boyeon Kim
- Department of Laboratory Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Yoonjung Kim
- Department of Laboratory Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Kyung-A Lee
- Department of Laboratory Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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Kaw A, Kaw K, Hostetler EM, Beleza-Meireles A, Smith-Collins A, Armstrong C, Scurr I, Cotts T, Aatre R, Bamshad MJ, Earl D, Groner A, Agre K, Raveh Y, Kwartler CS, Milewicz DM. Expanding ACTA2 genotypes with corresponding phenotypes overlapping with smooth muscle dysfunction syndrome. Am J Med Genet A 2022; 188:2389-2396. [PMID: 35567597 PMCID: PMC9283281 DOI: 10.1002/ajmg.a.62775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/13/2022] [Accepted: 04/09/2022] [Indexed: 11/07/2022]
Abstract
Pathogenic variants in ACTA2, encoding smooth muscle α-actin, predispose to thoracic aortic aneurysms and dissections. ACTA2 variants altering arginine 179 predispose to a more severe, multisystemic disease termed smooth muscle dysfunction syndrome (SMDS; OMIM 613834). Vascular complications of SMDS include patent ductus arteriosus (PDA) or aortopulmonary window, early-onset thoracic aortic disease (TAD), moyamoya-like cerebrovascular disease, and primary pulmonary hypertension. Patients also have dysfunction of other smooth muscle-dependent systems, including congenital mydriasis, hypotonic bladder, and gut hypoperistalsis. Here, we describe five patients with novel heterozygous ACTA2 missense variants, p.Arg179Gly, p.Met46Arg, p.Thr204Ile, p.Arg39Cys, and p.Ile66Asn, who have clinical complications that align or overlap with SMDS. Patients with the ACTA2 p.Arg179Gly and p.Thr204Ile variants display classic features of SMDS. The patient with the ACTA2 p.Met46Arg variant exhibits exclusively vascular complications of SMDS, including early-onset TAD, PDA, and moyamoya-like cerebrovascular disease. The patient with the ACTA2 p.Ile66Asn variant has an unusual vascular complication, a large fusiform internal carotid artery aneurysm. The patient with the ACTA2 p.Arg39Cys variant has pulmonary, gastrointestinal, and genitourinary complications of SMDS but no vascular manifestations. Identifying pathogenic ACTA2 variants associated with features of SMDS is critical for aggressive surveillance and management of vascular and nonvascular complications and delineating the molecular pathogenesis of SMDS.
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Affiliation(s)
- Anita Kaw
- Division of Medical Genetic, Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Kaveeta Kaw
- Division of Medical Genetic, Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Ellen M Hostetler
- Division of Medical Genetic, Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Ana Beleza-Meireles
- Bristol Regional Clinical Genetics Service, St Michael's Hospital, Bristol, UK
| | - Adam Smith-Collins
- Regional Neonatal Intensive Care Unit, St Michael's Hospital, Bristol, UK
| | | | - Ingrid Scurr
- Bristol Regional Clinical Genetics Service, St Michael's Hospital, Bristol, UK
| | - Timothy Cotts
- Division of Pediatric Cardiology, Department of Pediatrics, Michigan Medicine, University of Michigan at Ann Arbor, Ann Arbor, Michigan, USA
| | - Rajani Aatre
- Franklin Cardiovascular Center, Department of Internal Medicine, Michigan Medicine, University of Michigan at Ann Arbor, Ann Arbor, Michigan, USA
| | - Michael J Bamshad
- Division of Medical Genetics, Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Dawn Earl
- Division of Medical Genetics, Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Abraham Groner
- Division of Cardiology, Department of Pediatrics, The University of Chicago, Chicago, Illinois, USA
| | | | - Yehuda Raveh
- Department of Anesthesia, University of Miami/Jackson Memorial Hospital, Miami, Florida, USA
| | - Callie S Kwartler
- Division of Medical Genetic, Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Dianna M Milewicz
- Division of Medical Genetic, Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA
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