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X-linked sideroblastic anemia
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X-linked sideroblastic anemia

Reviewed October 2006

What is X-linked sideroblastic anemia?

X-linked sideroblastic anemia is an inherited disorder that prevents red blood cells (erythrocytes) from making sufficient hemoglobin, the iron-containing protein that carries oxygen in the blood. In X-linked sideroblastic anemia, red blood cells cannot use iron efficiently to make hemoglobin. As a result, the body tries to compensate by absorbing more iron from the diet. Iron that is not incorporated into hemoglobin builds up in other tissues and organs in the body, where it can cause damage.

The signs and symptoms of this disorder range from mild to severe and usually begin by the age of 30. The characteristic features of this disorder include pale skin, fatigue, dizziness, and an enlarged spleen and liver. Heart disease, liver damage, and kidney failure are severe medical problems that can result from the buildup of iron in these organs.

How common is X-linked sideroblastic anemia?

This form of anemia is very rare; several hundred cases have been reported worldwide.

What genes are related to X-linked sideroblastic anemia?

Mutations in the ALAS2 gene cause X-linked sideroblastic anemia.

Mutations in the HFE gene modify the course of X-linked sideroblastic anemia.

The ALAS2 gene provides instructions for making an enzyme called ALA-synthase, which is critical in the chemical process that leads to heme production. Heme is part of the hemoglobin protein and is vital for supplying oxygen to the entire body. When the ALAS2 gene is mutated, heme cannot be produced normally. As a result, not enough hemoglobin is made, allowing iron to build up and damage the body's tissues.

People who inherit mutations in the HFE gene, along with a mutation in the ALAS2 gene, may experience particularly severe signs and symptoms of X-linked sideroblastic anemia. Mutations in the HFE gene can also lead to increased absorption of iron from the diet and result in hemochromatosis, which is another type of iron overload disorder. A more serious iron overload can occur from the combined effect of these two mutations on iron absorption.

Read more about the ALAS2 and HFE genes.

How do people inherit X-linked sideroblastic anemia?

This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation usually must be present in both copies of the gene to cause the disorder. Males are affected by X-linked recessive disorders much more frequently than females. Some females with one altered copy of the ALAS2 gene may exhibit some signs and symptoms related to this condition. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

Where can I find information about treatment for X-linked sideroblastic anemia?

These resources address the management of X-linked sideroblastic anemia and may include treatment providers.

You might also find information on treatment of X-linked sideroblastic anemia in Educational resources and Patient support.

Where can I find additional information about X-linked sideroblastic anemia?

You may find the following resources about X-linked sideroblastic anemia helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for X-linked sideroblastic anemia?

  • Anemia, hereditary sideroblastic
  • Anemia, sex-linked hypochromic sideroblastic
  • ANH1
  • Congenital sideroblastic anaemia
  • Erythroid 5-aminolevulinate synthetase deficiency
  • Hereditary iron-loading anemia
  • Hypochromic anemia
  • X chromosome-linked sideroblastic anemia
  • X-linked pyridoxine-responsive sideroblastic anemia
  • XLSA

What if I still have specific questions about X-linked sideroblastic anemia?

Where can I find general information about genetic conditions?

What glossary definitions help with understanding X-linked sideroblastic anemia?

anemia ; cell ; chromosome ; congenital ; deficiency ; enlarged spleen ; enzyme ; erythrocyte ; gene ; heme ; hemoglobin ; hypochromic ; inheritance ; iron ; kidney ; mutation ; oxygen ; protein ; recessive ; red blood cell ; sex chromosomes ; sign ; symptom ; synthetases ; tissue ; trait ; X-linked recessive

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

References (10 links)


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

Reviewed: October 2006
Published: January 23, 2009