title: Mutations in the A3 domain of von Willebrand factor inducing combined qualitative and quantitative defects in the protein.
abstract: Two unrelated families were recruited in the French Reference Center for von Willebrand Disease with moderate bleeding symptoms associated with low von Willebrand factor (VWF) antigen levels, decreased collagen binding assay, and no or partial response to desmopressin. Genetic analysis showed the presence of heterozygous mutations in the A3 domain away from the collagen-binding surface: 1 never reported previously (p.L1696R) and another (p.P1824H) described in a Spanish family. The mutations were reproduced by site-directed mutagenesis and mutant VWF was expressed in different expression systems, COS-7 cells, baby hamster kidney cells, and in VWF-deficient mice through hydrodynamic injection. p.L1696R and p.P1824H were associated with very low expression levels both in vitro and in vivo, with intracellular retention for p.P1824H. Both homozygous mutants displayed decreased binding to collagen types I and III but also decreased binding to platelet glycoproteins Ib and IIbIIIa. Co-transfections with wild-type VWF partially corrected these defects, except that collagen binding remained abnormal. The in vivo thrombosis response was severely reduced for both heterozygous mutants. In conclusion, we report 2 VWF A3 domain mutations that induce a combined qualitative and quantitative defect.
authors: INSERM Unit 770, Le Kremlin-Bicêtre, France.
authors: Paulette
authors: P
authors: Legendre
authors: Ana-Maria
authors: AM
authors: Navarrete
authors: Julie
authors: J
authors: Rayes
authors: Caterina
authors: C
authors: Casari
authors: Pierre
authors: P
authors: Boisseau
authors: Catherine
authors: C
authors: Ternisien
authors: Claudine
authors: C
authors: Caron
authors: Edith
authors: E
authors: Fressinaud
authors: Jenny
authors: J
authors: Goudemand
authors: Agnès
authors: A
authors: Veyradier
authors: Cécile V
authors: CV
authors: Denis
authors: Peter J
authors: PJ
authors: Lenting
authors: Olivier D
authors: OD
authors: Christophe
mesh_terms: D000328:Adult; D000818:Animals; D000831:Animals, Newborn; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D006224:Cricetinae; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D020125:Mutation, Missense / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D014162:Transfection; D014842:von Willebrand Diseases / Q000235:genetics / Q000378:metabolism; D014841:von Willebrand Factor / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology*
chemical_list: D050505:Mutant Proteins; D014841:von Willebrand Factor