Another study, a 25-year cohort study [24], identified the prevalence of renal failure at 4.2% in patients with sickle cell anemia (median age of onset was 23.1, range 13-57 years) and 2.4% in patients with Hb-SC SCD (median age of onset was 49.9, range 29-65 years). The gene discussed is GSTM1; the disease is Schnyder corneal dystrophy.