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Factor VII gene intronic mutation in a lethal factor VII deficiency: effects on splice-site selection
Keren Borensztajn1, Marie-Laure Sobrier, Anne-Marie Fischer
1INSERM U428, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris V, France.
Blood
|April 5, 2003
Summary
Lethal factor VII deficiency in a patient resulted from two F7 gene mutations. These mutations activated a cryptic splice site, leading to a truncated protein and explaining the severe phenotype.
Area of Science:
- Genetics
- Molecular Biology
- Hematology
Background:
- Factor VII (FVII) deficiency can be severe and life-threatening.
- Genetic mutations in the F7 gene are responsible for FVII deficiency.
- Understanding splicing defects is crucial for explaining disease phenotypes.
Observation:
- A patient with lethal FVII deficiency presented with two homozygous nucleotide substitutions in the F7 gene.
- One mutation affected the IVS7 donor splice site, located within a minisatellite repeat.
- The second mutation resulted in a missense variation (Arg224Gln).
Findings:
- Minigene assays demonstrated that the mutant splice site led to aberrant F7 splicing.
- Normal splicing was abolished in cells transfected with the mutant construct.
- Spliced transcripts incorporated the first minisatellite repeat, activating a cryptic pseudo-site and generating a truncated protein.
Implications:
- These findings elucidate a novel splicing mechanism involving the selection of a single splice site among multiple cryptic sites.
- The identified mutations and resulting splicing defect provide a molecular explanation for the patient's lethal FVII deficiency.
- This study highlights the importance of splice site analysis in diagnosing genetic bleeding disorders.