Partial F8 gene duplication (factor VIII Padua) associated with high factor VIII levels and familial thrombophilia

Paolo Simioni, Stefano Cagnin, Francesca Sartorello, Gabriele Sales, Luca Pagani, Cristiana Bulato, Sabrina Gavasso, Francesca Nuzzo, Francesco Chemello, Claudia M. Radu, Daniela Tormene, Luca Spiezia, Tilman M. Hackeng, Elena Campello, Elisabetta Castoldi

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


High coagulation factor VIII (FVIII) levels comprise a common risk factor for venous thromboembolism (VTE), but the underlying genetic determinants are largely unknown. We investigated the molecular bases of high FVIII levels in 2 Italian families with severe thrombophilia. The proband of the first family had a history of recurrent VTE before age 50 years, with extremely and persistently elevated FVIII antigen and activity levels (>400%) as the only thrombophilic defects. Genetic analysis revealed a 23.4-kb tandem duplication of the proximal portion of the F8 gene (promoter, exon 1, and a large part of intron 1), which cosegregated with high FVIII levels in the family and was absent in 103 normal controls. Targeted screening of 50 unrelated VTE patients with FVIII levels ≥250% identified a second thrombophilic family with the same F8 rearrangement on the same genetic background, suggesting a founder effect. Carriers of the duplication from both families showed a twofold or greater upregulation of F8 messenger RNA, consistent with the presence of open chromatin signatures and enhancer elements within the duplicated region. Testing of these sequences in a luciferase reporter assay pinpointed a 927-bp region of F8 intron 1 associated with >45-fold increased reporter activity in endothelial cells, potentially mediating the F8 transcriptional enhancement observed in carriers of the duplication. In summary, we report the first thrombophilic defect in the F8 gene (designated FVIII Padua) associated with markedly elevated FVIII levels and severe thrombophilia in 2 Italian families.

Original languageEnglish (US)
Pages (from-to)2383-2393
Number of pages11
Issue number17
StatePublished - Apr 29 2021
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology


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