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N-Terminal Variant p.Ala2Val in X-Linked Dyskeratosis Congenita Gene (DKC1) Disrupts Its Post-Translational
Taimoor I Sheikh1,2,3, John B Vincent1,4,5
1Molecular Neuropsychiatry & Development (MiND) Lab, Molecular Brain Science Research Department, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
Molecular Genetics & Genomic Medicine
|August 13, 2026
Summary
The DKC1 p.(Ala2Val) variant causes protein mis-localization and altered modifications, suggesting it is pathogenic. This functional evidence aids in reclassifying the variant for dyskeratosis congenita diagnosis.
Area of Science:
- Genetics
- Molecular Biology
- Cell Biology
Background:
- Dyskeratosis congenita (DKC) is a rare genetic disorder characterized by physical abnormalities and progressive bone marrow failure.
- DKC is often linked to pathogenic variants in the DKC1 gene, increasing risks for hematologic malignancies and solid tumors.
- The DKC1 c.5C>T (p.Ala2Val) variant is of uncertain significance due to a lack of functional data.
Purpose of the Study:
- To investigate the functional impact of the DKC1 p.(Ala2Val) variant.
- To determine the cellular localization and post-translational modification status of the p.(Ala2Val) DKC1 protein.
- To provide evidence for variant reclassification in clinical diagnostics.
Main Methods:
- Co-localization studies using GFP-tagged WT and p.(Ala2Val) DKC1 constructs in HEK293T cells.
- Liquid Chromatography Mass Spectrometry (LCMS) analysis of immunoprecipitated WT and p.(Ala2Val) DKC1.
- Assessment of protein localization (nucleolus vs. nucleoplasm) and post-translational modifications (N-terminal methionine cleavage, N-acetylation).
Main Results:
- The p.(Ala2Val) DKC1 variant causes mis-localization of the protein from the nucleolus to the nucleoplasm.
- While N-terminal methionine cleavage occurs for both WT and p.(Ala2Val) DKC1, N-acetylation is observed only for WT DKC1.
- These findings indicate altered post-translational modification patterns for the p.(Ala2Val) variant.
Conclusions:
- The functional data demonstrate that p.(Ala2Val) DKC1 exhibits aberrant cellular localization and post-translational modification.
- This provides strong evidence to reclassify the p.(Ala2Val) variant as "pathogenic" according to ACMG guidelines.
- The study aids clinical laboratories in accurate variant interpretation for DKC diagnosis.
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