title: F8 gene dosage defects in atypical patients with severe haemophilia A.
abstract: We performed molecular analysis of the factor 8 gene (F8) in 272 unrelated Spanish patients with haemophilia A (HA) and detected a mutation by routine analysis in 267 of them (98.1%). No mutation was detected in the remaining five patients despite clinical and laboratory confirmation of HA. The aim is to describe the molecular alterations in F8 discovered by gene dosage methodologies in three of these patients. For methodology, F8 sequencing, intragenic marker analysis, multiplex ligation-dependent probe amplification and quantitative real time-PCR were followed. One patient had Klinefelter syndrome (47,XXY) and a large deletion spanning exons 1-12 masked by the other F8 allele; the second patient showed a large duplication spanning exons 2-10 and the third patient revealed a non-contiguous double duplication of exons 14 and 23-25. The remaining two patients had mild HA and dosage results were normal. The application of gene dosage methods is useful to define haemophilic patients in whom mutations are not detected using other routine methods. Nevertheless, in a small percentage of patients (<1%), no molecular pathology can be identified after testing several genetic methodologies.
authors.affiliation: Department of Genetics, Hospital de Sant Pau, Barcelona and CIBERER U-705, Spain.
authors.forename: Á
authors.initials: Á
authors.lastname: Venceslá
authors.forename: M
authors.initials: M
authors.lastname: Baena
authors.forename: R P
authors.initials: RP
authors.lastname: Garrido
authors.forename: R
authors.initials: R
authors.lastname: Núñez
authors.forename: F
authors.initials: F
authors.lastname: Velasco
authors.forename: J
authors.initials: J
authors.lastname: Rosell
authors.forename: A
authors.initials: A
authors.lastname: Villar
authors.forename: V
authors.initials: V
authors.lastname: Jiménez-Yuste
authors.forename: M
authors.initials: M
authors.lastname: Baiget
authors.forename: E F
authors.initials: EF
authors.lastname: Tizzano
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D004252:DNA Mutational Analysis; D005091:Exons; D005169:Factor VIII / Q000235:genetics*; D018628:Gene Dosage; D020440:Gene Duplication; D006467:Hemophilia A / Q000150:complications / Q000235:genetics*; D006801:Humans; D007713:Klinefelter Syndrome / Q000150:complications / Q000235:genetics; D008297:Male; D060885:Multiplex Polymerase Chain Reaction; D010375:Pedigree; D017384:Sequence Deletion; D013030:Spain
chemical_list: D005169:Factor VIII