Clinical and laboratorial characterization of a cohort of patients with hereditary platelet disorders

Introduction: Inherited platelet disorders (IPDs) are rare conditions characterized by altered platelet function (IPFDs) and/or reduced platelet counts (IPNDs). Diagnosing IPDs is challenging which may results in delays, misdiagnosis and unappropriated treatment. In low and middle-income countries data on these disorders are scarce. Here, we describe a cohort of IPD patients at a reference center in Brazil. Methods: A descriptive analysis was conducted on patients with suspected or diagnosed IPDs at the Thrombosis and Hemostasis outpatient clinic of the Hospital das Clinicas, University of São Paulo, Brazil. From 857 patients identified between 1998 and 2023, 60 met the eligibility criteria for suspected or confirmed IPDs. Patients with acquired causes of platelet dysfunction were excluded. Results: The cohort comprised 60 patients, 65% with IPFDs and 35%, IPNDs. Women were 75%, with a median age of 48 years. IPDs were suspected based on clinical history, family history, and laboratory tests. In the IPND group, 62% had a family history of thrombocytopenia. In the IPFD group, family history was positive in 51% of cases. Previous misdiagnosis included ITP (immune thrombocytopenia) and von Willebrand disease. The bleeding phenotype, assessed using the ISTH BAT (Bleeding Assessment Tool) score, showed a median score of 6, with IPNDs scoring lower than IPFDs. Conclusions: Identifying IPDs is essential for proper treatment and follow-up. This study emphasizes the need for careful assessment of the familial history, bleeding risk, platelet count, morphology and function in diagnosing IPDs, particularly in low resource settings without access to advanced genetic testing.