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Mohajeri A, Vaseghi-Shanjani M, Rosenfeld JA, Yang GX, Lu H, Sharma M, Lin S, Salman A, Waqas M, Sababi Azamian M, Worley KC, Del Bel KL, Kozak FK, Rahmanian R, Biggs CM, Hildebrand KJ, Lalani SR, Nicholas SK, Scott DA, Mostafavi S, van Karnebeek C, Henkelman E, Halparin J, Yang CL, Armstrong L, Turvey SE, Lehman A. Dominant negative variants in IKZF2 cause ICHAD syndrome, a new disorder characterised by immunodysregulation, craniofacial anomalies, hearing impairment, athelia and developmental delay. J Med Genet 2023; 60:1092-1104. [PMID: 37316189 DOI: 10.1136/jmg-2022-109127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 12/27/2022] [Accepted: 05/29/2023] [Indexed: 06/16/2023]
Abstract
BACKGROUND Helios (encoded by IKZF2), a member of the Ikaros family of transcription factors, is a zinc finger protein involved in embryogenesis and immune function. Although predominantly recognised for its role in the development and function of T lymphocytes, particularly the CD4+ regulatory T cells (Tregs), the expression and function of Helios extends beyond the immune system. During embryogenesis, Helios is expressed in a wide range of tissues, making genetic variants that disrupt the function of Helios strong candidates for causing widespread immune-related and developmental abnormalities in humans. METHODS We performed detailed phenotypic, genomic and functional investigations on two unrelated individuals with a phenotype of immune dysregulation combined with syndromic features including craniofacial differences, sensorineural hearing loss and congenital abnormalities. RESULTS Genome sequencing revealed de novo heterozygous variants that alter the critical DNA-binding zinc fingers (ZFs) of Helios. Proband 1 had a tandem duplication of ZFs 2 and 3 in the DNA-binding domain of Helios (p.Gly136_Ser191dup) and Proband 2 had a missense variant impacting one of the key residues for specific base recognition and DNA interaction in ZF2 of Helios (p.Gly153Arg). Functional studies confirmed that both these variant proteins are expressed and that they interfere with the ability of the wild-type Helios protein to perform its canonical function-repressing IL2 transcription activity-in a dominant negative manner. CONCLUSION This study is the first to describe dominant negative IKZF2 variants. These variants cause a novel genetic syndrome characterised by immunodysregulation, craniofacial anomalies, hearing impairment, athelia and developmental delay.
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Affiliation(s)
- Arezoo Mohajeri
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Maryam Vaseghi-Shanjani
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Gui Xiang Yang
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Henry Lu
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Mehul Sharma
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Susan Lin
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Areesha Salman
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Meriam Waqas
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Mahshid Sababi Azamian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Kim C Worley
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Kate L Del Bel
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Frederick K Kozak
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Ronak Rahmanian
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Catherine M Biggs
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Kyla J Hildebrand
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Seema R Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Sarah K Nicholas
- Department of Pediatrics, Texas Children's Hospital, Houston, Texas, USA
| | - Daryl A Scott
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Sara Mostafavi
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Clara van Karnebeek
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Erika Henkelman
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Jessica Halparin
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Connie L Yang
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Linlea Armstrong
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
- Provincial Medical Genetics Program, BC Children's & Women's Hosp, Vancouver, British Columbia, Canada
| | - Stuart E Turvey
- Department of Pediatrics, The University of British Columbia and BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Anna Lehman
- Department of Medical Genetics, The University of British Columbia, Vancouver, British Columbia, Canada
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Dailey-Schwartz AL, Tadros HJ, Azamian MS, Lalani SR, Morris SA, Allen HD, Kim JJ, Landstrom AP. Copy Number Variants of Undetermined Significance Are Not Associated with Worse Clinical Outcomes in Hypoplastic Left Heart Syndrome. J Pediatr 2018; 202:206-211.e2. [PMID: 30172441 PMCID: PMC6203622 DOI: 10.1016/j.jpeds.2018.07.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/18/2018] [Accepted: 07/05/2018] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To determine the prevalence, spectrum, and prognostic significance of copy number variants of undetermined significance (cnVUS) seen on chromosomal microarray (CMA) in neonates with hypoplastic left heart syndrome (HLHS). STUDY DESIGN Neonates with HLHS who presented to Texas Children's Hospital between June 2008 and December 2016 were identified. CMA results were abstracted and compared against copy number variations (CNVs) in ostensibly healthy individuals gathered from the literature. Findings were classified as normal, consistent with a known genetic disorder, or cnVUS. Survival was then compared using Kaplan-Meier analysis. Secondary outcomes included tracheostomy, feeding tube at discharge, cardiac arrest, and extracorporeal membrane oxygenation (ECMO). RESULTS Our study cohort comprised 105 neonates with HLHS, including 70 (66.7%) with normal CMA results, 9 (8.6%) with findings consistent with a known genetic disorder, and 26 (24.7%) with a cnVUS. Six of the 26 (23.0%) neonates with a cnVUS had a variant that localized to a specific region of the genome seen in the healthy control population. One-year survival was 84.0% in patients with a cnVUS, 68.3% in those with normal CMA results, and 33.3% in those with a known genetic disorder (P = .003). There were no significant differences in secondary outcomes among the groups, although notably ECMO was used in 15.7% of patients with normal CMA and was not used in those with cnVUS and abnormal results (P = .038). CONCLUSIONS Among children with HLHS, cnVUSs detected on CMA are common. The cnVUSs do not localize to specific regions of the genome, and are not associated with worse outcomes compared with normal CMA results.
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Affiliation(s)
- Andrew L. Dailey-Schwartz
- Department of Pediatrics, Section of Cardiology, Baylor College of Medicine, Houston, Texas, United States
| | - Hanna J. Tadros
- Department of Pediatrics, Section of Cardiology, Baylor College of Medicine, Houston, Texas, United States
| | - Mahshid Sababi Azamian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Seema R. Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States
| | - Shaine A Morris
- Department of Pediatrics, Section of Cardiology, Baylor College of Medicine, Houston, Texas, United States
| | - Hugh D. Allen
- Department of Pediatrics, Section of Cardiology, Baylor College of Medicine, Houston, Texas, United States
| | - Jeffrey J. Kim
- Department of Pediatrics, Section of Cardiology, Baylor College of Medicine, Houston, Texas, United States
| | - Andrew P. Landstrom
- Department of Pediatrics, Section of Cardiology, Baylor College of Medicine, Houston, Texas, United States.,† Address for Correspondence:Andrew P. Landstrom, MD, PhD Texas Children’s Hospital 1102 Bates Avenue Feigin Center, Suite 430.09 Houston TX 77030, United States Phone: (832) 824-4122 Fax: (832) 825-0237
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