Rare factor VII variant inherited through genetic variant in proband's mother and another genetic variant in...

An 11-year-old girl with hereditary factor-VII deficiency and her family have been studied for factor VII coagulation activity (VII:C) and factor VII antigen level (VII:Ag). The proband had 11% VII:C, whereas her VII:Ag was at a level that corresponds to about 50% coagulation activity. Forty-two members of the proband's family were tested. This study disclosed that the proband's factor VII deficiency had been inherited through both her mother and her father. Although her father was dead, testing of her father's family showed a factor VII defect of the type VII+ variant, that is, normal production of VII:Ag but reduced VII:C. The maternal side of her family was found to have reduced but identical levels of VII:C and VII:Ag (variant VIIR). The proband's factor VII deficiency is therefore apparently inherited through two different variants, and that could explain this rare genetic type of factor VII deficiency. To our knowledge no such variant has ever been described.