Diagnosis of von Willebrand disease in Western Mexico.

INTRODUCTION: Von Willebrand disease (VWD) is the most common inherited bleeding disorder with a prevalence of 0.1%, characterised by quantitative or functional deficiency of von Willebrand factor (VWF). VWD diagnosis is based on symptomology, biochemical and genetic tests, but limited laboratory resources and VWD heterogeneity still generate an important subdiagnosis gap worldwide and in our country. AIM: To identify the type and subtype of VWD in a cohort of patients with a history of excessive bleeding in Western Mexico. METHODS: This prospective cohort study from 2012 to 2019 included patients with mucocutaneous bleeding or abnormal laboratory tests. A standardised questionnaire and confirmatory tests were applied: FVIII:C, VWF activity, VWF antigen, and VWF multimeric analysis. RESULTS: Of the 297 patients recruited, 207 (69.7%) were excluded because their values exceeded 50% in VWF activity and VWF antigen. Of those 90 remaining, 54 (18.2%) had low VWF, and only 36 patients (12.1%) were diagnosed with VWD. Among them, 17 (47.2%) had quantitative deficiencies, of whom 14 were assigned as type 1 and 3 as type 3.The remaining 19 cases were diagnosed as type 2 (52.8%): type 2A and 2B were the most frequent with 6 and 7 cases respectively; 4 cases were possible type 2M and two suggestive of 2N, however, this was not confirmed. CONCLUSION: This study highlights the challenges of VWD diagnosis using a comprehensive panel of diagnostic tests which should extend to supplemental tests of VWF:CB, VWF:FVIIIB, and sequencing the VWD gene to confirm the results from the panel assays.

[Diagnostic algorithm for von Willebrand Disease (vWD) in a Mexican population]. / Algoritmo diagnóstico para la enfermedad de von Willebrand (EvW) en población mexicana.

The diagnosis of von Willebrand disease (vWD) is complex and requires several screening and confirmation tests, such as the analysis of vWF multimers, which is considered the gold standard for vWD subtyping; however, it only discriminates 2A subtype while the 2B, 2M, and 2N subtypes require additional tests and even genetic testing for final confirmation. It is important to consider the patients' hemotype for the vWD diagnosis, particularly in Mexico where hemotype "O" predominates and may entail a 20-25% decreased level of plasma vWF and increased bleeding tendency.