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Klein A, Klug K, Breyer M, Grüner J, Medala VK, Nordbeck P, Wanner C, Klopocki E, Üçeyler N. Genetic variants of unknown significance in alpha-galactosidase A: Cellular delineation from Fabry disease. J Inherit Metab Dis 2024. [PMID: 38618884 DOI: 10.1002/jimd.12743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 04/16/2024]
Abstract
Fabry disease (FD) is an X-linked multiorgan disorder caused by variants in the alpha-galactosidase A gene (GLA). Depending on the variant, disease phenotypes range from benign to life-threatening. More than 1000 GLA variants are known, but a link between genotype and phenotype in FD has not yet been established for all. p.A143T, p.D313Y, and p.S126G are frequent examples of variants of unknown significance (VUS). We have investigated the potential pathogenicity of these VUS combining clinical data with data obtained in human cellular in vitro systems. We have analyzed four different male subject-derived cell types for alpha-galactosidase A enzyme (GLA) activity and intracellular Gb3 load. Additionally, Gb3 load in skin tissue as well as clinical data were studied for correlates of disease manifestations. A reduction of GLA activity was observed in cells carrying p.A143T compared with controls (p < 0.05). In cells carrying the p.D313Y variant, a reduced GLA activity was found only in endothelial cells (p < 0.01) compared with controls. No pathological changes were observed in cells carrying the p.S126G variant. None of the VUS investigated caused intracellular Gb3 accumulation in any cell type. Our data of aberrant GLA activity in cells of p.A143T hemizygotes and overall normal cellular phenotypes in cells of p.D313Y and p.S126G hemizygotes contribute a basic science perspective to the clinically highly relevant discussion on VUS in GLA.
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Affiliation(s)
- Alexandra Klein
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Katharina Klug
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Maximilian Breyer
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Julia Grüner
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | | | - Peter Nordbeck
- University Hospital Würzburg, Fabry Centre for Interdisciplinary Therapy Würzburg (FAZIT), Würzburg, Germany
- Department of Internal Medicine 1, Division of Cardiology, University Hospital Würzburg, Würzburg, Germany
| | - Christoph Wanner
- University Hospital Würzburg, Fabry Centre for Interdisciplinary Therapy Würzburg (FAZIT), Würzburg, Germany
- Department of Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Eva Klopocki
- University of Würzburg, Institute for Human Genetics, Würzburg, Germany
| | - Nurcan Üçeyler
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
- University Hospital Würzburg, Fabry Centre for Interdisciplinary Therapy Würzburg (FAZIT), Würzburg, Germany
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