Publication Only: Bleeding disorders (congenital and acquired)
Combined factor VII (FVII) and factor X (FX) deficiency is considered as an extremely rare bleeding disorder. Only a few cases have been reported all over the world. According to the WFH (World Federation of Hemophilia) 2014, the global populations' prevalence of combined defects of coagulation factors (CDCF) is close to 1:2 000 000. These recessively inherited coagulation disorders, are usually associated with a high consanguinity's rate. Unfortunately, diagnosis is still underestimated, mainly due to the important heterogeneity of clinical and biological phenotypes which may induce difficulties in the disease's management in patients.
The aim of this study was to report two cases presenting a combined FVII-FX deficiency diagnosed in the South of Tunisia.
Biological investigation included prothrombin time (PT), activated partial thromboplastin time, FVII and FX analysis by coagulometric methods and fibrinogen by the Clauss method.
An 11-year-old female was referred to our laboratory to realize routine screening tests before a tonsillectomy. Haemostasis has been checked and results showed a prolonged PT (PT = 45%, normal range:70-100%) (aPTT and fibrinogen were normal), which prompted to realize further tests. Our patient, offspring of a consanguineous marriage, reported, since an early age, recurrent epistaxis and abundant gingivorrhagia. Laboratory analyses showed a combined FVII and FX deficiency with a mild decrease of both FVII and FX coagulant activities as follows: (FVII:C = 52%, normal range: 55-170%) and FX:C = 36%, normal range: 70-120%) which required a family screening. It was then revealed that she had an older sister (17 years old) with a combined FVII and FX deficiency (FVII:C = 53%, FX:C = 47%). Clinically, the sister presented gingivorrhagia since an early age. With regard to the parents, the plasma levels of the father revealed that he was probably a carrier of FX deficiency (FX:C = 51%) and he complained about gingivorrhagia and epistaxis too. However, the mother and two other sisters had normal coagulant activities and didn't suffer from any abnormal bleeding disorder.
In accordance with the recent reports, the presence of two clotting defects in a patient may cause diagnostic difficulties. For that, firstly, an acquired vitamin K deficiency should be excluded by getting normal clotting activities of both factors II and IX. Secondly, to avoid a misdiagnosis, it's recommended to investigate both FVII and FX in cases with prolonged PT, especially that patients belonging to the South of Tunisia are known by high rates of consanguineous marriages. Added to that, it's important to explore the mutational spectrum of F7 and F10 and its associated phenotypes in order to attest the combined defects and to guarantee a better genetic counselling.