1
|
Gunsel AS, Ergoren MC, Kemal H, Kafshboran HR, Cerit L, Turgay A, Duygu H. Determination of Carrier Frequency of Actionable Pathogenic Variants in Autosomal Recessive Genetic Diseases in the Turkish Cypriot Population. Genes (Basel) 2023; 14:1967. [PMID: 37895316 PMCID: PMC10606490 DOI: 10.3390/genes14101967] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/04/2023] [Accepted: 10/19/2023] [Indexed: 10/29/2023] Open
Abstract
Whole-exome DNA sequencing is a rich source of clinically useful information for specialists, patients, and their families, as well as elucidating the genetic basis of monogenic and complex diseases in clinical diagnosis. However, interpreting and reporting variants encompassing exome and genome sequence analysis outcome data are one of the greatest challenges of the genomic era. In this study, we aimed to investigate the frequency and allele frequency spectrum of single nucleotide variants accepted as recessive disease carrier status in Turkish Cypriot exomes. The same sequencing platform and data processing line were used for the analysis of data from 100 Turkish Cypriot whole-exome sequence analysis. Identified variants were classified according to ACMG guidelines, and pathogenic variants were confirmed in other databases such as ClinVar, HGMD, Varsome, etc. Pathogenic variants were detected in 68 genes out of 100 whole-exome sequence data. The carriage rate was the highest in the CYP21A2 gene, causing 21-hydroxylase deficiency (14.70%), 11.76% in the HBB gene causing β-thalassemia, 10.29% in the BTD gene causing biotinidase deficiency, 8.82% in the CFTR gene causing cystic fibrosis, 8.82% in the RBM8A gene causing thrombocytopenia-absent radius syndrome, which is an ultra-rare disease, and 5.88% in the GAA gene causing glycogen storage disease II. The carriage of pathogenic variants in other genes causing the disease (GJB2, PAH, GALC, CYP11B2, COL4A3, HBA1, etc.) was determined as less than 5.00%. Also, the identified variations in the mentioned gene within the examined population were reported. The most prevalent mutation in North Cyprus was a missense variant (c.1360 C>T, p.Pro454Ser) detected in the CYP21A2 gene (rs6445), and the most frequently seen variant in the HBB gene was c.93-21G>A (rs35004220). We investigated reported pathogenic variants by estimating the lower and upper limits of carrier and population frequencies for autosomal recessive diseases, for which exome sequencing may reveal additional medically relevant information. Determining the lower and upper limits of these frequencies will shed light on preventive medicine practices and governmental actions.
Collapse
Affiliation(s)
- Aziz Suat Gunsel
- Department of Cardiology, Faculty of Medicine, Near East University, Nicosia 99138, Cyprus; (A.S.G.); (H.K.); (L.C.); (H.D.)
| | - Mahmut Cerkez Ergoren
- Department of Medical Genetics, Faculty of Medicine, Near East University, Nicosia 99138, Cyprus;
- Laboratory of Medical Genetics, Near East University Hospital, Near East University, Nicosia 99138, Cyprus;
| | - Hatice Kemal
- Department of Cardiology, Faculty of Medicine, Near East University, Nicosia 99138, Cyprus; (A.S.G.); (H.K.); (L.C.); (H.D.)
| | | | - Levent Cerit
- Department of Cardiology, Faculty of Medicine, Near East University, Nicosia 99138, Cyprus; (A.S.G.); (H.K.); (L.C.); (H.D.)
| | - Ayla Turgay
- Laboratory of Medical Genetics, Near East University Hospital, Near East University, Nicosia 99138, Cyprus;
| | - Hamza Duygu
- Department of Cardiology, Faculty of Medicine, Near East University, Nicosia 99138, Cyprus; (A.S.G.); (H.K.); (L.C.); (H.D.)
| |
Collapse
|
2
|
Lyulcheva-Bennett E, Genomics England Research Consortium, Bennett D. A retrospective analysis of phosphatase catalytic subunit gene variants in patients with rare disorders identifies novel candidate neurodevelopmental disease genes. Front Cell Dev Biol 2023; 11:1107930. [PMID: 37056996 PMCID: PMC10086149 DOI: 10.3389/fcell.2023.1107930] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 03/03/2023] [Indexed: 03/30/2023] Open
Abstract
Rare genetic disorders represent some of the most severe and life-limiting conditions that constitute a considerable burden on global healthcare systems and societies. Most individuals affected by rare disorders remain undiagnosed, highlighting the unmet need for improved disease gene discovery and novel variant interpretation. Aberrant (de) phosphorylation can have profound pathological consequences underpinning many disease processes. Numerous phosphatases and associated proteins have been identified as disease genes, with many more likely to have gone undiscovered thus far. To begin to address these issues, we have performed a systematic survey of de novo variants amongst 189 genes encoding phosphatase catalytic subunits found in rare disease patients recruited to the 100,000 Genomes Project (100 kGP), the largest national sequencing project of its kind in the United Kingdom. We found that 49% of phosphatases were found to carry de novo mutation(s) in this cohort. Only 25% of these phosphatases have been previously linked to genetic disorders. A gene-to-patient approach matching variants to phenotypic data identified 9 novel candidate rare-disease genes: PTPRD, PTPRG, PTPRT, PTPRU, PTPRZ1, MTMR3, GAK, TPTE2, PTPN18. As the number of patients undergoing whole genome sequencing increases and information sharing improves, we anticipate that reiterative analysis of genomic and phenotypic data will continue to identify candidate phosphatase disease genes for functional validation. This is the first step towards delineating the aetiology of rare genetic disorders associated with altered phosphatase function, leading to new biological insights and improved clinical outcomes for the affected individuals and their families.
Collapse
Affiliation(s)
| | | | - Daimark Bennett
- Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| |
Collapse
|
3
|
Cediel ML, Stawarski M, Blanc X, Nosková L, Magner M, Platzer K, Gburek-Augustat J, Baldridge D, Constantino JN, Ranza E, Bettler B, Antonarakis SE. GABBR1 monoallelic de novo variants linked to neurodevelopmental delay and epilepsy. Am J Hum Genet 2022; 109:1885-1893. [PMID: 36103875 PMCID: PMC9606381 DOI: 10.1016/j.ajhg.2022.08.010] [Citation(s) in RCA: 1] [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] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 08/15/2022] [Indexed: 01/25/2023] Open
Abstract
GABAB receptors are obligatory heterodimers responsible for prolonged neuronal inhibition in the central nervous system. The two receptor subunits are encoded by GABBR1 and GABBR2. Variants in GABBR2 have been associated with a Rett-like phenotype (MIM: 617903), epileptic encephalopathy (MIM: 617904), and milder forms of developmental delay with absence epilepsy. To date, however, no phenotypes associated with pathogenic variants of GABBR1 have been established. Through GeneMatcher, we have ascertained four individuals who each have a monoallelic GABBR1 de novo non-synonymous variant; these individuals exhibit motor and/or language delay, ranging from mild to severe, and in one case, epilepsy. Further phenotypic features include varying degrees of intellectual disability, learning difficulties, autism, ADHD, ODD, sleep disorders, and muscular hypotonia. We functionally characterized the four de novo GABBR1 variants, p.Glu368Asp, p.Ala397Val, p.Ala535Thr, and p.Gly673Asp, in transfected HEK293 cells. GABA fails to efficiently activate the variant receptors, most likely leading to an increase in the excitation/inhibition balance in the central nervous system. Variant p.Gly673Asp in transmembrane domain 3 (TMD3) renders the receptor completely inactive, consistent with failure of the receptor to reach the cell surface. p.Glu368Asp is located near the orthosteric binding site and reduces GABA potency and efficacy at the receptor. GABA exhibits normal potency but decreased efficacy at the p.Ala397Val and p.Ala535Thr variants. Functional characterization of GABBR1-related variants provides a rationale for understanding the severity of disease phenotypes and points to possible therapeutic strategies.
Collapse
Affiliation(s)
- Maria Lucia Cediel
- Medigenome, Swiss Institute of Genomic Medicine, 1207 Geneva, Switzerland
| | - Michal Stawarski
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Xavier Blanc
- Medigenome, Swiss Institute of Genomic Medicine, 1207 Geneva, Switzerland
| | - Lenka Nosková
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Martin Magner
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic; Department of Pediatrics, First Faculty of Medicine, Charles University and University Thomayer Hospital in Prague, Prague, Czech Republic
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Janina Gburek-Augustat
- Division of Neuropaediatrics, Hospital for Children and Adolescents, University Hospital Leipzig, Leipzig, Germany
| | | | | | - Emmanuelle Ranza
- Medigenome, Swiss Institute of Genomic Medicine, 1207 Geneva, Switzerland
| | - Bernhard Bettler
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | | |
Collapse
|
4
|
Hansen AW, Arora P, Khayat MM, Smith LJ, Lewis AM, Rossetti LZ, Jayaseelan J, Cristian I, Haynes D, DiTroia S, Meeks N, Delgado MR, Rosenfeld JA, Pais L, White SM, Meng Q, Pehlivan D, Liu P, Gingras MC, Wangler MF, Muzny DM, Lupski JR, Kaplan CD, Gibbs RA. Germline mutation in POLR2A: a heterogeneous, multi-systemic developmental disorder characterized by transcriptional dysregulation. HGG Adv 2021; 2:100014. [PMID: 33665635 PMCID: PMC7928427 DOI: 10.1016/j.xhgg.2020.100014] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 11/06/2020] [Indexed: 12/23/2022] Open
Abstract
De novo germline variation in POLR2A was recently reported to associate with a neurodevelopmental disorder. We report twelve individuals harboring putatively pathogenic de novo or inherited variants in POLR2A, detail their phenotypes, and map all known variants to the domain structure of POLR2A and crystal structure of RNA polymerase II. Affected individuals were ascertained from a local data lake, pediatric genetics clinic, and an online community of families of affected individuals. These include six affected by de novo missense variants (including one previously reported individual), four clinical laboratory samples affected by missense variation with unknown inheritance-with yeast functional assays further supporting altered function-one affected by a de novo in-frame deletion, and one affected by a C-terminal frameshift variant inherited from a largely asymptomatic mother. Recurrently observed phenotypes include ataxia, joint hypermobility, short stature, skin abnormalities, congenital cardiac abnormalities, immune system abnormalities, hip dysplasia, and short Achilles tendons. We report a significantly higher occurrence of epilepsy (8/12, 66.7%) than previously reported (3/15, 20%) (p value = 0.014196; chi-square test) and a lower occurrence of hypotonia (8/12, 66.7%) than previously reported (14/15, 93.3%) (p value = 0.076309). POLR2A-related developmental disorders likely represent a spectrum of related, multi-systemic developmental disorders, driven by distinct mechanisms, converging at a single locus.
Collapse
Affiliation(s)
- Adam W. Hansen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Payal Arora
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michael M. Khayat
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Leah J. Smith
- Department of Biochemistry and Biophysics, Texas A&M University, TX, USA
| | - Andrea M. Lewis
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Linda Z. Rossetti
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Joy Jayaseelan
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - Ingrid Cristian
- Division of Genetics, Arnold Palmer Hospital for Children, Orlando Health, Orlando, FL, USA
| | - Devon Haynes
- Division of Genetics, Arnold Palmer Hospital for Children, Orlando Health, Orlando, FL, USA
| | - Stephanie DiTroia
- Broad Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Naomi Meeks
- Departments of Pediatrics and Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Mauricio R. Delgado
- Texas Scottish Rite Hospital for Children, Dallas, TX, USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jill A. Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Baylor Genetics Laboratories, Houston, TX, USA
| | - Lynn Pais
- Broad Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Susan M. White
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Parkville 3052, VIC, Australia
- Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Qingchang Meng
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - Davut Pehlivan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Pengfei Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Baylor Genetics Laboratories, Houston, TX, USA
| | - Marie-Claude Gingras
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX, USA
| | - Michael F. Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, USA
| | - Donna M. Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - James R. Lupski
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Texas Children’s Hospital, Houston, TX, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Craig D. Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Richard A. Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| |
Collapse
|
6
|
Abstract
Despite advances in high-throughput sequencing that have revolutionized the discovery of gene defects in rare Mendelian diseases, there are still gaps in translating individual genome variation to observed phenotypic outcomes. While we continue to improve genomics approaches to identify primary disease-causing variants, it is evident that no genetic variant acts alone. In other words, some other variants in the genome (genetic modifiers) may alleviate (suppress) or exacerbate (enhance) the severity of the disease, resulting in the variability of phenotypic outcomes. Thus, to truly understand the disease, we need to consider how the disease-causing variants interact with the rest of the genome in an individual. Here, we review the current state-of-the-field in the identification of genetic modifiers in rare Mendelian diseases and discuss the potential for future approaches that could bridge the existing gap.
Collapse
Affiliation(s)
- K. M. Tahsin Hassan Rahit
- Departments of Biochemistry, Molecular Biology and Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada;
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Maja Tarailo-Graovac
- Departments of Biochemistry, Molecular Biology and Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada;
- Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| |
Collapse
|