Sideroblastic anemia

A disease in which the bone marrow produces ringed sideroblasts rather than healthy red blood cells and it may be caused either by a genetic disorder or indirectly as part of normal nucleated erythroblasts with granules of iron accumulated in perinuclear mitochondria.

Sideroblastic anemia is divided into subtypes based on its cause.

Hereditary or congenital sideroblastic anemia may be X-linked or autosomal.

X-linked sideroblastic anemia is associated with ALAS2 gene.

Sideroblastic anemia with spinocerebellar ataxia (ASAT) is associated with ABCB7 gene.

Pyridoxine-refractory autosomal recessive sideroblastic anemia associated with SLC25A38 gene.

Pyridoxine-responsive sideroblastic anemia, vitamin B6 deficiency; pyridoxal phosphate required for heme synthesis associated with GLRX5 gene.

Acquired, or secondary, sideroblastic anemia develops after birth.

Symptoms include: pallor, fatigue, dizziness and hepatosplenomegaly.

Heart disease, liver damage and kidney failure can result from accumulation of iron stores.

Associated with failure to completely form heme molecules in the mitochondria, and causes accumulation of iron in the form of a ring around the nucleusof the developing red blood cell.

Associated with lead, copper or zinc toxicity, and may be related to ethanol, INH, chloramphenicol, oral contraceptives, cycloserine, copper deficiency and Vitamin B6 deficiency.

Findings on peripheral smear may include dimorphic anemia with anisocytosis and poikilocytosis, basophilic stippling, target cells and Pappenheimer bodies.

Associated with microcytosis with a normal or low MCV.

RDW is increased.

Bone marrow shows erythroid hyperplasia with a maturation arrest, and an excess of 40% of the developing erythrocytes are ringed sideroblasts, and increased stainable marrow iron.

Serum iron and f2241itin levels are increased and the TIBC is normal to decreased, and the transf2241in level is elevated.

Transfusion therapy may be required and patients do not respond to erythropoietin therapy.

Some patients respond to moderate to high doses of pyrodoxine (Vitamin B6).

80% of heriditary cases are responsive to pyridoxine, though the hematologic abnormalities do not revert completely to normal.

Primary acquired sideroblastic anemia patients are responsive to Vitamin B6 in 405 of cases, but the response may be minor.

Secondary siderblastic anemia is 60% responsive.

In severe cases bone marrow transplant is an option.

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