Genetic Influence of Genetic Factors Influencing the Desmopressin's Efficacy in Mild/Moderate Hemophilia A

Hemophilia A (HA) is an X-linked bleeding disorder caused by mutations in the F8 gene. Bleeding in patients with moderate/mild HA can be treated with either FVIII concentrates or desmopressin (DDAVP). This drug acts as a vasopressin type 2-receptor agonist that causes endothelial cells to rapidly secrete von Willebrand factor (VWF) and factor VIII (FVIII) into the bloodstream. One advantage of DDAVP is that it increases the level of endogenous FVIII, thus avoiding the need for potentially immunogenic exogenous FVIII. It is also cheaper than FVIII concentrates. Finally, it is more widely available in pharmacies in all hospitals with emergency rooms and surgical facilities. DDAVP usually increases the basal FVIII (FVIII activity) level by 3- to 4-fold. Thus, complete correction of the FVIII level (\>0.5 IU.mL-1) was achieved in different series as early as 1 hour after its administration in 50-60% of patients with mild HA. Since responses to DDAVP vary widely between individuals, it is recommended that each patient undergoes a therapeutic test before treatment. Several factors influence the FVIII response to DDAVP. The two most important are basal FVIII levels and the F8 gene defect. Rare studies related to the effect of genotype on DDAVP responses, but included relatively small patient groups (\<100), with few patients sharing a similar genotype. As such, it has been difficult from a statistical point of view to formally demonstrate the influence of the F8 genotype on the DDAVP response. The objectives of the GIDEMHA study (Genetic Influence of Desmopressin Efficacy in Mild/moderate Hemophilia A) are: description of the post-DDAVP FVIII pharmacokinetics (PK) in a large retrospective cohort of patients with mild/moderate HA, research of patients-related factors influencing this FVIII PK, and building of predictive population- and Bayesian-based models. The study comprises 2 independent cohorts: * GIDEMHA-1 includes patients who had a DDAVP test from 2010 to 2020 in 4 centers. The influence of F8 variants on post-DDAVP FVIII PK is first analyzed then age, VWF level, blood group, weigh and DDAVP doses. * GIDEMHA-2 includes patients who had a DDAVP test from 2020 to 2023 in the previous 4 centers (Angers, Caen, Nantes and Rennes) plus patients who had a DDAVP test from 2010 to 2023 in 2 other centers (Brest and Tours). This is a replicative cohort allowing to build predictive models based on the above described influencing factors.

Sex

Male

Minimum age

2 Years

Maximum age

80 Years

Inclusion Criteria:

* Males with a mild or moderate hemophilia A,
* Therapeutic test with desmopressin realized in the last 10 years,
* Factor VIII levels measurements realized at least 2 times during the therapeutic test, just before the desmopressin infusion and 30 or 60 minutes after,
* Complete genotyping of the F8 gene for genetic diagnosis of hemophilia

Exclusion Criteria:

* Patients with an anti-factor VIII inhibitor
* Refusal to participate in the study
* Unable to understand the study's French letter of non-opposition and information