Sickle beta-plus thalassemia is a form of sickle cell disease. It describes the condition resulting from a hybrid of two genetic defects in the gene for making hemoglobin - an essential component of red blood cells. It occurs in the presence of one allele for sickling (deformed) hemoglobin, and one allele for moderate beta thalassemia. Sickle beta-plus thalassemia closely resembles a mild case of a sickle cell anemia. It is a lifelong condition, but not necessarily debilitating.