Second-line options for ITP include thrombopoietin receptor agonists (TPO-RAs) and rituximab (unlicensed for ITP) [7], while fostamatinib is an option in the United Kingdom (UK) for patients with refractory ITP previously treated with a TPO-RA, or if a TPO-RA is unsuitable [10]. The gene discussed is MPL; the disease is autoimmune thrombocytopenic purpura.