A key finding of our study is that 87.5% of genetically confirmed MYH9-RD patients were initially misdiagnosed and treated ITP, consistent with previously reported misdiagnosis rates of inherited platelet disorders [2,3] The consequences were substantial: unnecessary exposure to corticosteroids and IVIG in 7 of 8 patients, delayed molecular diagnosis (median 24 months; up to 11 years), Escalation to second-line therapies including thrombopoietin receptor agonists or repeated immunosuppression in some cases. Here, MPL is linked to blood platelet disease.