GSTM1 and autosomal dominant cerebellar ataxia: First, although it is sometimes difficult to distinguish Hb SS from Hb Sβ0 thalassemia based on results of hemoglobin electrophoresis or other non DNA tests, there is no single ICD-9-CM code for SCA, rather there are separate codes for “hemoglobin-SS disease with/without crisis” (282.61, 282.62) and “sickle-cell thalassemia with/without crisis” (282.41, 282.42).