GSTM1 and thalassemia: To address these gaps in our knowledge, we evaluated the utility of the uACR as well as genetic, clinical, and laboratory risk factors associated with eGFR decline in a longitudinal registry of adults with hemoglobin (Hb) SS or Sβ0‐thalassemia sickle cell disease from the United States and repeated our analyses in a separate cohort of adults with Hb SS or Sβ0‐thalassemia sickle cell disease from France.