Factor VIII mutation and desmopressin-responsiveness in 62 patients with mild haemophilia A

Utilization of the synthetic vasopressin analogue (1-deamino-8-D-arginine-vasopressin, DDAVP) in treatment of mild haemophilia A (MHA, specific clotting factor VIII activity level 0.05-0.4 IU mL(-1) ) is convenient and effective for many but not all patients. Genetic testing for patients with MHA is increasingly recognized as providing valuable information for patient care beyond informing reproductive decisions, and as more patients are genotyped, mutation data can be utilized to individualize treatment decisions. To determine if genetic information informs response to DDAVP, a retrospective chart review was performed under Institutional Review Board approval to extract patient data with MHA, genetic mutation results, and response to DDAVP challenge. 62 patients met inclusion criteria. Complete responses (C) presented in mean value IU mL(-1) (range), were recorded for 32 of 62(52%) subjects: pre 0.19(0.04-0.45) and post 0.78(0.5-1.95); partial responses (P) were recorded for 15 of 62(24%) subjects: pre 0.1(0.06-0.15) and post 0.4(0.3-0.47); responses that were not clinically significant (N) were recorded for 15 of 62(24%) subjects: pre 0.17(0.02-0.34) and post 0.25(0.03-0.44). Subjects (related and unrelated) with the same mutation showed a trend towards a similar response to DDAVP. Eight genotypes were common to two or more subjects (n = 26). Two genotypes were concordant in all subjects [p.Ser2192Ile n = 3(C), p.Ala2220Pro n = 2(P)]. Of mutations in the C1 or C2 domains, 13 of 15(87%) subjects responded to DDAVP [C = 9(60%); P = 4(27%); n = 2(13%)]. Baseline FVIII:C did not predict magnitude of response to DDAVP. Genetic mutation results can assist with predicting DDAVP responsiveness, but baseline FVIII:C may not.