title: Glanzmann's thrombasthenia caused by homozygosity for a splice defect that leads to deletion of the first coding exon of the glycoprotein IIIa mRNA.
abstract: Glanzmann's thrombasthenia (GT) is the result of the absence or of an altered and dysfunctional expression on the platelet membrane of the fibrinogen receptor (glycoprotein [GP] IIb/IIIa complex). Various molecular genetic mechanisms have been found to be responsible for this inherited disease. In a patient with a severe type of GT, we have found a splice variant in the GP IIIa gene that leads to premature chain termination. Immunoprecipitation experiments, using monoclonal antibodies specific for GP IIb/IIIa, showed that GP IIb/IIIa was not detectable on the platelet membrane. Amplification of reversely transcribed platelet GP IIIa mRNA by the polymerase chain reaction and subsequent sequence analysis showed a 86-bp deletion, which corresponds to exon i of the GP IIIa gene. This deletion results in a shift of the reading frame leading to eight altered amino acids followed by a premature termination codon. Analysis of the corresponding genomic DNA fragments showed three mutations in the exon i-intron i boundary region of the GP IIIa gene. One of these mutations is a G-->T transition that eliminates the GT splice donor site in the wild type. This base pair change creates a restriction site for the enzyme Mse I. Allele-specific restriction enzyme analysis (ASRA) with Mse I of amplified genomic DNA of the parents and the proposita showed that both parents (who are first cousins) are heterozygous, whereas the proposita is homozygous for the G-->T substitution.
authors: Department of Immunological Haematology, Central Laboratory of the Netherlands, Red Cross Blood Transfusion Service, Amsterdam.
authors: S
authors: S
authors: Simsek
authors: H
authors: H
authors: Heyboer
authors: L G
authors: LG
authors: de Bruijne-Admiraal
authors: R
authors: R
authors: Goldschmeding
authors: H T
authors: HT
authors: Cuijpers
authors: A E
authors: AE
authors: von dem Borne
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D001792:Blood Platelets / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D015252:Deoxyribonucleases, Type II Site-Specific; D005091:Exons; D005260:Female; D017353:Gene Deletion; D006720:Homozygote; D006801:Humans; D007163:Immunosorbent Techniques; D008969:Molecular Sequence Data; D010980:Platelet Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000097:blood / Q000235:genetics*; D013915:Thrombasthenia / Q000097:blood / Q000235:genetics*
chemical_list: D000911:Antibodies, Monoclonal; D010980:Platelet Membrane Glycoproteins; D012333:RNA, Messenger; D004247:DNA; C055927:endodeoxyribonuclease MseI; D015252:Deoxyribonucleases, Type II Site-Specific