Subtype of myelodysplastic syndrome with iron accumulation in red blood cell precursor mitochondria.
Refractory anemia with ring sideroblasts is a type of myelodysplastic syndrome.
RARS is characterized by 5% or less myeloblasts in bone marrow. RARS is distinguished from refractory anemia by having 15% or more ringed sideroblasts among the erythroid precursors in the bone marrow.
Refractory anemia with ringed sideroblasts in transformation-10-30% of cases, 21-30% blasts, 50-60% transformation to AML.
Recurrent mutation of the SF3B1 gene is found in 20% of patients with myelodysplastic syndromes.
SF3B1 gene mutations are found in 65% of patients with ring sideroblastic anemias, and even among other subtypes of myelodysplastic syndromes with large numbers of ring sideroblasts in the marrow, such a gene mutation frequency is common.
SF3B1 mutations related to subtype refractory anemia with ringed sideroblasts, associated with improved prognosis.
Refractory anemia with the ring sideroblasts generally have a benign clinical course (Malcovati L et al).
Patients with refractory anemia and refractory anemia with ringed sideroblasts have a low risk for progression to acute myeloid leukemia.
More than 25% of cases have large numbers of ring sideroblasts in the bone marrow.
Ring sideroblasts usually seen on iron staining of marrow aspirate erythrocytes with a complete or partial ring of iron laden mitochondria surrounding the nucleus.
Patients with refractory anemia and refractory anemia with ringed sideroblasts have anemia as a result of ineffective erythropoiesis and high rate of erythroid apoptosis.