Novel mutations in congenital factor XII deficiency

Area of Science:

• Genetics
• Hematology
• Molecular Biology

Background:

• Congenital Factor XII (FXII) deficiency is a rare bleeding disorder.
• Several mutations in the F12 gene have been linked to FXII deficiency.

Purpose of the Study:

• To identify and characterize novel mutations in the F12 gene causing congenital FXII deficiency.
• To elucidate the molecular mechanisms underlying FXII deficiency in affected patients.

Main Methods:

• Genetic sequencing of the F12 gene in five patients with congenital FXII deficiency.
• In vitro studies using transfected HEK 293T cells to assess FXII levels.
• Protein degradation inhibition experiments to investigate degradation pathways.

Main Results:

• Identified three F12 gene mutations: p.G259E, p.R267G, and p.E521K.
• Mutations significantly reduced FXII levels in cell culture media without affecting transcription.
• Mutant FXII proteins were degraded intracellularly via the proteasome pathway.
• p.G259E and p.R267G mutations showed dominant negative effects.

Conclusions:

• The identified F12 gene mutations are causative for cross-reactive material-negative FXII deficiencies.
• Intracellular proteasomal degradation is a key mechanism in these FXII deficiency cases.
• Dominant negative effects of certain mutations contribute to the clinical phenotype.