Inherited thromboxane A synthase 1 (TBXAS1) mutations cause GHDD, which leads to enlargement of the long bone diaphysis and bone marrow failure. Affected patients often require frequent transfusion support, and empiric treatment with steroids is sometimes effective. Treatment with NSAIDs (aspirin and ibuprofen) at intermediate to high doses, which inhibits COX-1 and COX-2, reverse aberrant prostaglandin and leukotriene metabolite production in GHDD, leading to restored hematopoiesis. RBC, red blood cell; WBC, white blood cell.