SMARCB1 and kidney medullary carcinoma: SMARCB1-deficient renal medullary carcinoma (RMC) is a rare but aggressive subtype of renal cell carcinoma (RCC) that primarily affects adolescents and young adults (AYAs) with underlying sickle hemoglobinopathies, such as sickle cell trait and sickle cell disease (1–4).