Curtailing the Path From Epistaxis to Genetics: The Diagnostic Value of Detailed Medical History in Hereditary Macrothrombocytopenia.

Hereditary macrothrombocytopenias represent a heterogeneous group of inherited platelet disorders that may present with variable, often mild, bleeding symptoms and are frequently misdiagnosed as acquired thrombocytopenias. This report presents a four-year-old boy with recurrent severe epistaxis and a family history of increased bleeding tendencies accompanied by low platelet counts. The patient had mild thrombocytopenia, large platelets, and a slightly prolonged platelet function analysis, while standard coagulation studies and thromboelastography were within normal limits. Next-generation sequencing identified a heterozygous variant in the alpha-actinin-1 (ACTN1) gene, confirming the diagnosis of ACTN1-related thrombocytopenia. Management consisted of supportive care and observation. This case underscores the significance of genetic testing in the diagnostic evaluation of suspected hereditary thrombocytopenias to facilitate accurate diagnosis, prevent unnecessary interventions, and enable appropriate genetic counseling for affected families.