What characterizes sideroblastic anemia?

Sideroblastic anemia is characterized by a defect in hemoglobin synthesis resulting from impaired synthesis of heme, specifically due to defective protoporphyrin (which is a precursor to heme). In this condition, iron is present in the body but cannot be properly incorporated into hemoglobin, leading to the formation of ringed sideroblasts in the bone marrow, which are erythroblasts that contain excessive iron granules. These granules appear as concentric rings around the nucleus due to the failure of iron to be utilized for heme production.

In addition to this defective protoporphyrin synthesis, individuals with sideroblastic anemia often present with microcytic, hypochromic anemia due to reduced hemoglobin content within the red blood cells. Strikingly, despite the adequate or increased levels of iron in the body, the erythropoiesis process is ineffective, leading to anemia.

While iron overload in tissues is associated with sideroblastic anemia, it is the impaired protoporphyrin synthesis that specifically defines the pathophysiology of the condition. Other options, such as defective hemoglobin synthesis or bone marrow fibrosis, do not accurately describe the core defect related to sideroblastic anemia.