Characterization of Bleeding and Laboratory Phenotype in Hemophilia A Carriers: A Cross-Sectional Study in Benin

Background: In Africa, hemophilia is underdiagnosed and carriers have long been considered free from bleeding symptoms. However, recent research has begun to reveal hemostatic abnormalities and bleeding manifestations in carriers of hemophilia A, particularly due to excessive inactivation of normal X chromosomes. Objective: To describe the bleeding symptoms and hemostatic abnormalities in carriers of hemophilia A (HA) in Benin. Methods: This study was conducted as a prospective cross-sectional investigation between April 2021 to March 2022. The study population consisted of identified through pedigrees of persons with hemophilia A being treated in various hospitals in Benin. Data were collected through interviews conducted by trained physician and each carrier underwent a biological workup. Results: A total of 71 hemophilia A carriers were included and 38 of whom were obligatory carriers. Thirty-one carriers (43.7%) reported abnormal bleeding symptoms. Menorrhagia has (71%) being the most important manifestation, followed by bleeding during or after childbirth (45.2%). Among the 71 carriers, 45 were of reproductive age. Of whom 22 (48.8%) had a Higham score exceeding 100. Activated partial thromboplastin time was prolonged in 7 carriers (9.9%). The mean activity factor VIII:C (FVIII:C) levels were 68.8 ± 34.9 IU/dL. The average FVIII:C level in obligatory carriers was 56.9% and among potential carriers, the average FVIII:C level was higher at 80.4%. However twelve female carriers (16.9%) had FVIII:C levels < 40%. The FVIII:C/FvWAg ratio was below 0.7 in 73.2% of female drivers. Obligatory carriers (p = 0.00003) and FVIII; C/FvWAg ratio < 0.7 (p = 0.003) were statistically associated with abnormal bleeding symptoms, while blood group O (p = 0.0002) and FVIII/FvWAg ratio < 0.7 (p = 0.0016) were associated with a higher risk of menorrhagia. Conclusion: In Benin, carriers of haemophilia A present bleeding symptoms and haemostatic abnormalities. Further studies on a larger number of carriers are needed to better characterize and manage these patients.