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Insertion of a C in the exon 28 of integrin αIIb gene leading to a frameshift mutation is responsible for Glanzmann thrombasthenia in a Japanese case
Author(s) -
HAYASHI T.,
TANAKA S.,
HORI Y.,
TERADA C.,
UEDA Y.,
TANI Y.
Publication year - 2005
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2005.01160.x
Subject(s) - microbiology and biotechnology , frameshift mutation , exon , transfection , thrombasthenia , glanzmann's thrombasthenia , fusion protein , mutation , expression vector , biology , gene , chemistry , genetics , platelet , immunology , recombinant dna , platelet aggregation
Summary. Background: Glanzmann thrombasthenia (GT) is a hereditary bleeding disorder caused by a qualitative or quantitative defect in the integrin αIIbβ3. Objective: Our objective is to identify the gene mutation that resulted in GT. Patients and methods: The patient was a 66‐year‐old male with a history of frequent bleeding. The expression levels of the integrin proteins in the platelets were determined by flow cytometry and Western blot analysis. The sequences of genomic DNA and mRNA encoding for αIIb and β3 were analyzed by the dye‐terminator cycle sequencing method. For transfection experiments, expression vectors encoding for wild‐type αIIb, mutated αIIb, β3, green fluorescent protein (GFP) fusion wild‐type αIIb, GFP fusion mutated αIIb and DsRed fusion β3 were constructed. These vectors were transfected to COS‐7 cells, and the expression levels were determined. Results: The αIIb protein was remarkably reduced in the patient's platelets, and gene analysis showed that the patient possessed compound heterozygous mutations in the αIIb gene. One was a C → G substitution at the splice acceptor site (− 3) of exon 26 ( C AG → G AG) and the other was the insertion of an additional C at the region including six C bases between 2911 and 2916 in exon 28 (InsC). Transfection experiments using COS‐7 cells showed that αIIb containing InsC had expressed and formed a complex with β3, but had not been transported to the Golgi apparatus. Conclusions: In the present study the novel mutation InsC, leading to a frameshift that affects the transmembrane domain and the cytoplasmic tail, was found to be responsible for GT.