Factor VII gene intronic mutation in a lethal factor VII deficiency: effects on splice-site selection.
In a patient with lethal factor VII (FVII) deficiency, 2 homozygous nucleotide substitutions were identified in the F7 gene: a IVS7+2T>G transversion involving the IVS7 donor splice site, followed by a mutation at nucleotide 10588 that would result in a missense variation (Arg224Gln). The mutated splice site, located within the first repeat of a minisatellite, is followed by a variable number of pseudo-sites, normally silent. To investigate the consequences of this mutation on F7 splicing, we designed normal and mutant minigenes, spanning exons 5 to 8. In cells transfected with the mutant construct, no normal splicing occurred. Only spliced transcripts including the first minisatellite repeat were observed, resulting from the activation of the most proximal wild-type pseudo-site, which would generate a truncated protein (stop codon upstream of nucleotide 10588). These findings, which suggest the existence of a mechanism selecting one single splice site among multiple cryptic sites, explain the patient's phenotype.
Borensztajn
Keren
K
INSERM U428, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris V, France.
Sobrier
Marie-Laure
ML
Fischer
Anne-Marie
AM
Chafa
Ouerdia
O
Amselem
Serge
S
Tapon-Bretaudiere
Jacqueline
J
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D005091:Exons / Q000235:genetics; D005167:Factor VII / Q000235:genetics*; D005168:Factor VII Deficiency / Q000235:genetics*; D005804:Genes, Lethal; D006801:Humans; D007438:Introns / Q000235:genetics*; D008957:Models, Genetic; D010641:Phenotype; D022821:RNA Splice Sites / Q000235:genetics*; D012326:RNA Splicing / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
D022821:RNA Splice Sites; D012333:RNA, Messenger; D005167:Factor VII