title: Common large partial VWF gene deletion does not cause alloantibody formation in the Hungarian type 3 von Willebrand disease population.
abstract: BACKGROUND
  Type 3 von Willebrand disease (VWD) is an autosomal recessive bleeding disorder, characterized by virtually undetectable plasma von Willebrand factor (VWF) and consequently reduced plasma factor VIII levels. Genetic mutations responsible for type 3 VWD are very heterogeneous, scattered throughout the VWF gene and show high variability among different populations.
  
  
  METHODS
  Twenty-five severe VWD patients were studied by direct sequencing of the 51 coding exons of the VWF gene. The total number of VWD type 3 families in Hungary is 24, of which 23 were investigated.
  
  
  RESULTS
  Fifteen novel mutations were identified in 31 alleles, five being nonsense mutations (p.Q1238X, p.Q1898X, p.Q1931X, p.S2505X and p.S2568X), four small deletions and insertions resulting in frame shifts (c.1992insC, c.3622delT, c.5315insGA and c.7333delG), one a large partial deletion (delExon1-3) of the 5'-region, four candidate missense mutations (p.C35R, p.R81G, p.C295S, p.C623T) and one a candidate splice site mutation (c.1730-10C>A). Six previously described mutations were detected in 17 alleles, including the repeatedly found c.2435delC, p.R1659X and p.R1853X. Only one patient developed alloantibodies to VWF, carrying a homozygous c.3622delT.
  
  
  CONCLUSIONS
  We report the genetic background of the entire Hungarian type 3 VWD population. A large novel deletion, most probably due to a founder effect, seems to be unique to Hungarian type 3 VWD patients with high allele frequency. In contrast to previous reports, none of the five patients homozygous for the large partial deletion developed inhibitors to VWF. This discrepancy raises the possibility of selection bias in some of the reports.
authors.affiliation: 2nd Department of Pediatrics, Semmelweis University, Budapest, Hungary.
authors.forename: A
authors.initials: A
authors.lastname: Mohl
authors.forename: Z
authors.initials: Z
authors.lastname: Boda
authors.forename: R
authors.initials: R
authors.lastname: Jager
authors.forename: H
authors.initials: H
authors.lastname: Losonczy
authors.forename: A
authors.initials: A
authors.lastname: Marosi
authors.forename: T
authors.initials: T
authors.lastname: Masszi
authors.forename: E
authors.initials: E
authors.lastname: Nagy
authors.forename: L
authors.initials: L
authors.lastname: Nemes
authors.forename: T
authors.initials: T
authors.lastname: Obser
authors.forename: F
authors.initials: F
authors.lastname: Oyen
authors.forename: G
authors.initials: G
authors.lastname: Radványi
authors.forename: Á
authors.initials: Á
authors.lastname: Schlammadinger
authors.forename: Z S
authors.initials: ZS
authors.lastname: Szélessy
authors.forename: A
authors.initials: A
authors.lastname: Várkonyi
authors.forename: K
authors.initials: K
authors.lastname: Vezendy
authors.forename: B
authors.initials: B
authors.lastname: Vilimi
authors.forename: R
authors.initials: R
authors.lastname: Schneppenheim
authors.forename: I
authors.initials: I
authors.lastname: Bodó
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D017353:Gene Deletion; D005838:Genotype; D006801:Humans; D006814:Hungary; D007518:Isoantibodies / Q000737:chemistry / Q000235:genetics; D008297:Male; D008957:Models, Genetic; D009154:Mutation; D020125:Mutation, Missense; D012042:Registries; D011795:Surveys and Questionnaires; D056729:von Willebrand Disease, Type 3 / Q000235:genetics*; D014841:von Willebrand Factor / Q000235:genetics*
chemical_list: D007518:Isoantibodies; D014841:von Willebrand Factor