X-linked sideroblastic anemia (XLSA) is a rare microcytic hypochromic anemia with iron overload and ring sideroblasts in the bone marrow. The disease can occur at any age. It is caused by pathogenic variants in the ALAS2 gene (loss of function mutations), which lead to a deficiency of delta-aminolaevulinic acid synthase and thus to impaired heme synthesis. The age of manifestation and the expression of symptoms are highly variable. Due to the X-linked inheritance, males are predominantly affected. However, heterozygous female carriers may also show symptoms. Diagnosis is made by determining the blood count, reticulocyte count, ferritin level, detection of ring sideroblasts in the bone marrow, and genetic analysis of the ALAS2 gene. Because of the risk of iron overload, an early diagnosis is important. There is the possibility of therapy with pyridoxine and folic acid, which, however, does not respond in all patients.
In addition to XLSA, several other congenital forms of sideroblastic anemia are known. Furthermore, sideroblastic anemias can also be acquired and triggered, for example, by drugs and alcohol.
Donker et al, Neth J Med. 2014 May;72(4):210-7 / Fleming MD, Semin Hematol. 2002 Oct;39(4):270-81 / May and Bishop, Haematologica. 1998 83(1):56-70 /