Research and Practice in Thrombosis and Haemostasis (RPTH) - Comprehensive Genotype and phenotype characterization in Non-severe Hemophilia A patients on assay discrepancies

Congreso

Summary *

Background: One-third of patients with non-severe Hemophilia A (nsHA) presents a discrepancy between the results of FVIII activity (FVIII:C) measured by one-stage-assay (OSA) and chromogenic-substrate-assays (CSA). It is observed that this situation can lead to misunderstanding the diagnostic in Hemophilia A (HA) or even worst to get a wrong classification regarding the severity of the disease.Aims: Consider the impact of the discrepancies between OSA and CSA, to face the diagnostic and classification of Patients with Hemophilia and also evaluate the F8-genotype and phenotype.Methods: 111 patients having bleeding disorders with a diagnostic of HA between 2012 and 2021 were evaluated. We performed laboratory hemostasis studies in all samples (Prothrombin time, Activated Partial thromboplastin time (aPTT), Thrombin Time (TT), aPTT 1:1 mix, OSA, CSA, vWF:Ag, vWF:CoR, Siemens Healthineers; Sysmex CS-2500). The Initial classification of the disease was performed with OSA (Severe Hemophilia A: sHA < 0.01 IU/mL, Moderate Hemophilia A: modHA 0.01-0.05 IU/mL, Mild Hemophilia A: miHA 0.05-0.40 IU/mL). FVIII discrepancy was defined as OSA/CSA ≤ 0.6 or CSA/OSA ≥ 1.5, correlating it with the clinical phenotype. Genotyping: PCR-amplification method followed by conformation sensitive gel electrophoresis (CSGE) and Sanger sequencing.Results: 81 patients were initially classified as sHA, and 30 patients were nsHA. 6 patients with nsHA showed discrepancies between the methods, F8-genotype was analyzed in the 6 cases. A comprehensive analysis of the correlation of genotype and phenotype is showed in Table 1 and Figure 1.Conclusion(s): 20% of patients with nsHA showed discrepancies. No discrepancies were found in patients with sHA. We conclude that non-severe haemophilia patients could benefit if chromogenic assay is included in diagnosing and classification of severity haemophilia, and it also could help to individualize group of patients that could receive early replacement treatment Information provided by the agent in SIGEVA