Improved detection of low-level GNAQ mosaicism in Sturge-Weber syndrome through affected tissue testing, deep sequencing, and HRM-qPCR
4 affiliations
- 1Neuromuscular Research and Diagnostics, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
- 2Epilepsy Center. Member of ERN EpiCARE. Department Pediatric and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
- 3Department of Paediatrics and Adolescent Medicine, Villach, Austria
- 4Center for Anatomy and Cell Biology, Medical University of Vienna, Währinger Straße 13, Vienna, 1090 Austria
Abstract
Background: Sturge-Weber syndrome (SWS) is a rare genetic neurocutaneous syndrome. While classical (type I) SWS is mainly caused by tissue-specific somatic mosaicism of a recurrent missense variant in the GNAQ gene, other genes have been implicated in SWS. Therefore, genetic testing at an early stage can support clinical management of affected children and genetic counselling of their families.
Methods: Thirteen type I SWS patients were enrolled in this study. In the majority, blood-based genetic testing did not lead to genetic confirmation. DNA isolated from tissue samples (lesional skin biopsies in n = 12 samples or affected brain tissue in n = 1 sample) was subjected to next-generation sequencing at high coverage. We also established and validated a high-resolution melt analysis quantitative PCR (HRM-qPCR) assay for specific detection of the recurrent GNAQ variant.
Results: In contrast to peripheral blood samples, tissue samples from all patients were found to harbor the hotspot GNAQ c.548G>A p.(Arg183Gln) variant at fractions ranging from 0.5% to 8.3%. Subsequently, presence of the variant was confirmed by HRM-qPCR, which was found to be sensitive enough to detect variants even at very low fractions (0.25%).
Conclusion: Data from our case series emphasize the importance of tissue-based analysis by deep sequencing to detect somatic mosaicism in SWS and suggest that HRM-qPCR is a powerful technique for the targeted confirmation of low-level somatic variants.
Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1186/s13023-026-04530-z.
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BibTeX
@article{lilja2026improved,
title = {{Improved detection of low-level GNAQ mosaicism in Sturge-Weber syndrome through affected tissue testing, deep sequencing, and HRM-qPCR}},
author = {Stephanie Lilja and Sarah Glatter and Magdalena Vass and Birgit Pimpel and Bernhard Rosensteiner and Amina Paquay and Iris Schmidt and Robert Birnbacher and Reginald E. Bittner and Martha Feucht and Wolfgang M. Schmidt},
journal = {Orphanet Journal of Rare Diseases},
year = {2026},
month = aug,
doi = {10.1186/s13023-026-04530-z},
url = {https://doi.org/10.1186/s13023-026-04530-z},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Improved detection of low-level GNAQ mosaicism in Sturge-Weber syndrome through affected tissue testing, deep sequencing, and HRM-qPCR
AU - Stephanie Lilja
AU - Sarah Glatter
AU - Magdalena Vass
AU - Birgit Pimpel
AU - Bernhard Rosensteiner
AU - Amina Paquay
AU - Iris Schmidt
AU - Robert Birnbacher
AU - Reginald E. Bittner
AU - Martha Feucht
AU - Wolfgang M. Schmidt
PY - 2026
DA - 2026/08/03
JO - Orphanet Journal of Rare Diseases
DO - 10.1186/s13023-026-04530-z
UR - https://doi.org/10.1186/s13023-026-04530-z
AB - Background: Sturge-Weber syndrome (SWS) is a rare genetic neurocutaneous syndrome. While classical (type I) SWS is mainly caused by tissue-specific somatic mosaicism of a recurrent missense variant in the GNAQ gene, other genes have been implicated in SWS. Therefore, genetic testing at an early stage can support clinical management of affected children and genetic counselling of their families. Methods: Thirteen type I SWS patients were enrolled in this study. In the majority, blood-based genetic testing did not lead to genetic confirmation. DNA isolated from tissue samples (lesional skin biopsies in n = 12 samples or affected brain tissue in n = 1 sample) was subjected to next-generation sequencing at high coverage. We also established and validated a high-resolution melt analysis quantitative PCR (HRM-qPCR) assay for specific detection of the recurrent GNAQ variant. Results: In contrast to peripheral blood samples, tissue samples from all patients were found to harbor the hotspot GNAQ c.548G>A p.(Arg183Gln) variant at fractions ranging from 0.5% to 8.3%. Subsequently, presence of the variant was confirmed by HRM-qPCR, which was found to be sensitive enough to detect variants even at very low fractions (0.25%). Conclusion: Data from our case series emphasize the importance of tissue-based analysis by deep sequencing to detect somatic mosaicism in SWS and suggest that HRM-qPCR is a powerful technique for the targeted confirmation of low-level somatic variants. Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1186/s13023-026-04530-z.
SN - 1750-1172
ER -