Abstract
Hereditary antithrombin (AT) deficiency is an autosomal dominant inherited thrombophilia. In three pedigrees of hereditary type I AT deficiency, we identified novel variants c.126delC (p.Lys43Serfs*7), c.165C > G (p.Tyr55*), and c.546delA (p.Lys182Asnfs*102) in the open reading frame encoding AT in each patient. Each of these aberrant variants leads to premature termination of AT protein synthesis. To investigate whether these abnormal variants are involved in the pathogenesis of type I AT deficiency, we analyzed the function of these variants in HEK293 cells. Results of western blot analysis and immunofluorescence microscopy showed that all abnormal variants were expressed intracellularly, but p.Lys43Serfs*7 and p.Tyr55* protein were aggregated in the cells. These three variants were not detected in the spent culture medium, indicating that these novel variants affect protein secretion. In summary, we suggest that these variants in the AT-encoding gene are translated in the cell, but form abnormal proteins that form aggregates and/or inhibit secretion. These results provide insight into novel mechanisms of type I AT deficiency and potential therapies for the condition.
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Acknowledgements
We are grateful to Prof. Hiroshi Kawasaki of the Department of Medical Neuroscience, Graduate School of Medical Sciences, Kanazawa University, for providing use of a confocal laser microscope. This work was supported by the MHLW Research Program on Rare and Intractable Diseases (Grant Number JPMH20FC1024 to EM) and by a Grant-in-Aid from the Ministry of Health, Labour and Welfare of Japan (Grant Number 20K22869-00 to SN).
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Imai, Y., Nagaya, S., Araiso, Y. et al. Identification and functional analysis of three novel genetic variants resulting in premature termination codons in three unrelated patients with hereditary antithrombin deficiency. Int J Hematol 117, 523–529 (2023). https://doi.org/10.1007/s12185-022-03509-3
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DOI: https://doi.org/10.1007/s12185-022-03509-3