Glanzmann's thrombasthenia due to a point mutation within intron 10 results in aberrant splicing of the beta3 gene.
Glanzmann's thrombasthenia (GT) is an hereditary bleeding disorder caused by a quantitative or qualitative defect in the integrin alphaIIbbeta3. We attempted to identify genetic defects responsible for a case of GT in Korea. The patient was a 6-year-old boy who had suffered from hemorrhage and purpura. The cDNAs of alphaIIb and beta3 were amplified by reverse transcription (RT)-PCR and were sequenced. RT-PCR of COS7 cells transfected with Exontrap vectors containing the beta3 genomic DNA fragments were performed to verify an aberrant splicing. Transient expression of alphaIIbbeta3 on transfected-COS7 cells was determined by flow cytometry, and the presence of alphaIIbbeta3 was confirmed by immunoprecipitation. We discovered an abnormality with the insertion of 38 bp between exon 10 and exon 11, including a stop codon, in beta3 cDNA. Sequence analysis of genomic DNA showed a point mutation, G-->T, at the position 29 107 of intron 10. RT-PCR analyses of COS7 cells transfected with Exontrap vector containing the mutant beta3 gene revealed that the point mutation at the position 29 107 of intron 10, G-->T, was responsible for an aberrant splicing in the beta3 gene. The transfection experiments and immunoprecipitation revealed the absence of alphaIIbbeta3 in the COS7 cells transfected with mutant gene. The mutation at the position 29 107 of intron 10, G-->T, in the beta3 genomic DNA was found to induce an aberrant splicing and to be responsible for GT in this patient.
Tanaka
S
S
Department of Research, Osaka Red Cross Blood Center, Osaka, Japan. seiken@a1.mbn.or.jp
Hayashi
T
T
Terada
C
C
Hori
Y
Y
Han
K S
KS
Ahn
H S
HS
Bourre
F
F
Tani
Y
Y
D017398:Alternative Splicing / Q000235:genetics*; D002648:Child; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D005434:Flow Cytometry; D006470:Hemorrhage / Q000209:etiology; D006801:Humans; D039661:Integrin beta3 / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D007438:Introns; D008297:Male; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D017354:Point Mutation; D011693:Purpura / Q000209:etiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013915:Thrombasthenia / Q000209:etiology / Q000235:genetics*; D014162:Transfection
D039661:Integrin beta3; D019039:Platelet Glycoprotein GPIIb-IIIa Complex