Mutation of the beta1-tubulin gene associated with congenital macrothrombocytopenia affecting microtubule assembly.
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Kunishima S, Kobayashi R, Itoh TJ, Hamaguchi M, Saito H
Mutation of the beta1-tubulin gene associated with congenital macrothrombocytopenia affecting microtubule assembly.
Blood. 2009 Jan 8;113(2):458-61. doi: 10.1182/blood-2008-06-162610. Epub 2008 Oct 10.
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- 18849486 [ View in PubMed]
- Abstract
Congenital macrothrombocytopenia is a genetically heterogeneous group of rare disorders. We identified the first TUBB1 mutation, R318W, in a patient with congenital macrothrombocytopenia. The patient was heterozygous for Q43P, but this single-nucleotide polymorphism (SNP) did not relate to macrothrombocytopenia. Although no abnormal platelet beta1-tubulin localization/marginal band organization was observed, the level of beta1-tubulin was decreased by approximately 50% compared with healthy controls. Large and irregular bleb protrusions observed in megakaryocytes derived from the patient's peripheral blood CD34(+) cells suggested impaired megakaryocyte fragmentation and release of large platelets. In vitro transfection experiments in Chinese hamster ovary (CHO) cells demonstrated no incorporation of mutant beta1-tubulin into microtubules, but the formation of punctuated insoluble aggregates. These results suggested that mutant protein is prone to aggregation but is unstable within megakaryocytes/platelets. Alternatively, mutant beta1-tubulin may not be transported from the megakaryocytes into platelets. W318 beta1-tubulin may interfere with normal platelet production, resulting in macrothrombocytopenia.