Missense changes in the catalytic domain of coagulation factor X account for minimal function preventing a perinatal lethal condition

Mattia Ferrarese, Marcello Baroni, Patrizia Della Valle, Ivana Spiga, Antonella Poloniato, Armando D'Angelo, Mirko Pinotti, Francesco Bernardi, Alessio Branchini

Research output: Contribution to journalArticlepeer-review


Introduction: Inherited deficiencies in the coagulation pathway provide diversified models to investigate the molecular bases of perinatal lethality associated with null-like variants. Differently from X-linked haemophilias, homozygous/doubly heterozygous null variants in the rare autosomally inherited deficiency of factor X (FX) might be incompatible with perinatal survival. Aim: To provide experimental evidence about the null/close-to-null FX function. Methods: The residual secreted (ELISA) and functional (thrombin generation assays) protein levels associated with the novel nonsense (c.1382G>A; p.Trp461Ter) and missense (c.752T>C; p.Leu251Pro) variants, found in the proposita with life-threatening symptoms at birth, were characterized through recombinant (r)FX expression. Results: The rFX-461Ter showed very low secretion and undetectable function. Expression and function of the predicted readthrough-deriving missense variants (rFX-461Tyr, rFX-461Gln) were also severely impaired. These unfavourable features, due to nucleotide and protein sequence constraints, precluded functional readthrough over the 461 stop codon. Differently, the poorly secreted rFX-251Pro variant displayed residual function that was characterized by anti-TFPI aptamer-based amplification or selective inhibition of activated FX function by fondaparinux in plasma and found to be reduced by approximately three orders of magnitude. Similarly to the rFX-251Pro, a group of catalytic domain missense variants cause poorly secreted molecules with modest function in FX-deficient patients with life-threatening symptoms. Conclusions: Our data, contributing to the knowledge of the very severe FX deficiency forms, support life-saving requirement of trace FX function, clearly exemplified by the dysfunctional but not completely inactive rFX-251Pro variant that, albeit with severely reduced function, is compatible with a residual activity ensuring minimal haemostasis and permitting perinatal survival.

Original languageEnglish
Pages (from-to)685-692
Number of pages8
Issue number4
Publication statusPublished - Jul 2019


  • factor X deficiency
  • missense variants
  • nonsense variants
  • null variants
  • recombinant proteins

ASJC Scopus subject areas

  • Hematology
  • Genetics(clinical)


Dive into the research topics of 'Missense changes in the catalytic domain of coagulation factor X account for minimal function preventing a perinatal lethal condition'. Together they form a unique fingerprint.

Cite this