title: Novel nonsense mutation in the platelet glycoprotein Ibbeta gene associated with Bernard-Soulier syndrome.
abstract: Bernard-Soulier syndrome (BSS) is an autosomal recessive bleeding disorder caused by quantitative or qualitative abnormalities in the glycoprotein (GP) Ib/IX/V complex, the platelet receptor for von Willebrand factor. This complex is composed of four subunits, GPIbalpha, GPIbbeta, GPIX, and GPV, and the coordinated assembly of GPIbalpha, GPIbbeta, and GPIX is required for the efficient surface expression of a functional complex. We report here a novel nonsense mutation of the GPIbbeta gene associated with BSS. Flow cytometric analysis of the patient's platelets showed markedly reduced GPIbalpha and absent GPIX surface expression. Immunoblot analysis of solubilized platelets showed that a small amount of GPIbalpha was detected; however, GPIbbeta and GPIX were undetectable. DNA sequencing analysis revealed a novel nonsense mutation of the GPIbbeta gene that converts Trp (TGG) to a stop codon (TAG) at residue 123. Transient transfection studies revealed that the mutant GPIbbeta polypeptide was not detected in the transfected 293T cells, suggesting that null expression of the mutant GPIbbeta impairs expression of the GPIbalpha and GPIX subunits and results in a BSS phenotype in the patient.
authors.affiliation: Japanese Red Cross Aichi Blood Center, Seto, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kunishima
authors.forename: Tadashi
authors.initials: T
authors.lastname: Matsushita
authors.forename: Takahiko
authors.initials: T
authors.lastname: Ito
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kamiya
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Saito
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics; D001606:Bernard-Soulier Syndrome / Q000235:genetics*; D018389:Codon, Nonsense / Q000235:genetics*; D004247:DNA / Q000097:blood / Q000235:genetics; D005434:Flow Cytometry; D005784:Gene Amplification; D005808:Genes, Recessive; D006801:Humans; D008297:Male; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000737:chemistry; D012016:Reference Values
chemical_list: D015703:Antigens, CD; D018389:Codon, Nonsense; D019038:Platelet Glycoprotein GPIb-IX Complex; D011994:Recombinant Proteins; D004247:DNA