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X-linked sideroblastic anemia and ataxia
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

X-linked sideroblastic anemia and ataxia

X-linked sideroblastic anemia and ataxia is a rare, X-linked condition primarily affecting males, characterized by a blood disorder called sideroblastic anemia and progressive problems with balance and coordination (ataxia) that appear early in life.

Overview

X-linked sideroblastic anemia and ataxia is a rare condition that is characterized by a blood disorder called sideroblastic anemia and movement problems known as ataxia. This condition primarily occurs in males.

Sideroblastic anemia is defined by a shortage of healthy red blood cells. Sideroblastic anemia occurs when developing red blood cells called erythroblasts do not make enough, which is the protein that carries oxygen in the blood. People with X-linked sideroblastic anemia and ataxia have red blood cells that are smaller than normal (microcytic) and appear pale (hypochromic) because of the shortage of hemoglobin. The anemia seen in people with this condition is typically mild.

X-linked sideroblastic anemia and ataxia leads to an abnormal accumulation of iron in red blood cells. The iron-loaded red blood cells, which are present in bone marrow, are called ring sideroblasts.

X-linked sideroblastic anemia and ataxia causes problems with balance and coordination that appear early in life. Ataxia can make it difficult to sit, stand, and walk unassisted. People with this condition may find it difficult to make rapid, alternating movements (dysdiadochokinesia), such as tapping their foot.

In addition to ataxia, people with this condition often have trouble coordinating movements that involve judging distance or scale (dysmetria), such as reaching out to grab an object. Affected individuals can also experience involuntary rhythmic shaking that worsens during movement (intention tremor). Mild speech difficulties (dysarthria) and abnormal eye movements have also been reported in some individuals with X-linked sideroblastic anemia and ataxia.

Frequency

X-linked sideroblastic anemia and ataxia is a rare disorder, although its exact prevalence is unknown.

Causes

Variants (also called mutations) in the ABCB7 gene cause X-linked sideroblastic anemia and ataxia. The ABCB7 gene provides instructions for making a protein that is critical for producing a component of hemoglobin called heme. Hemoglobin is vital for supplying oxygen to the entire body. The ABCB7 protein also plays a role in the formation of clusters of iron and sulfur atoms (Fe-S clusters). These clusters get incorporated into a variety of proteins that are necessary for many cell functions. The ABCB7 protein likely helps maintain an appropriate balance of iron (iron homeostasis) in erythroblasts.

ABCB7 gene variants lead to changes in the structure of the ABCB7 protein, disrupting its usual roles in heme synthesis. Anemia occurs when heme cannot be produced normally and red blood cells cannot make enough hemoglobin. It is likely that a lack of heme and proteins that contain Fe-S clusters disrupts cell functions, particularly in nerve cells, resulting in ataxia and the other movement problems seen in people with X-linked sideroblastic anemia with ataxia.

Gene Associated with X-linked Sideroblastic Anemia and Ataxia

  • ABCB7

Inheritance

X-linked sideroblastic anemia and ataxia is inherited in an X-linked pattern. A condition is considered X-linked if the altered gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes in each cell. In males (who have only one X chromosome), a variant in the only copy of the gene in each cell is sufficient to cause the condition. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

In females (who have two copies of the X chromosome), one ABCB7 gene variant typically does not cause the health problems that are associated with X-linked sideroblastic anemia and ataxia; however, they may have abnormally small, pale red blood cells that can be detected with a blood test.

Other Names

  • SCAX6
  • X-linked sideroblastic anaemia with ataxia
  • X-linked spinocerebellar ataxia-6 with or without sideroblastic anemia
  • XLSA/A

Frequently Asked Questions

X-linked sideroblastic anemia and ataxia is a progressive condition, meaning the neurological symptoms, particularly ataxia, tend to worsen gradually over time, starting in early life. While the anemia is usually mild and stable, the challenges with balance, coordination, and fine motor skills will likely increase, potentially impacting independence in daily activities. Regular neurological assessments and adjustments to therapy plans are important to manage the evolving symptoms.
The anemia in X-linked sideroblastic anemia and ataxia is typically mild. Management often involves monitoring iron levels, as there can be an abnormal accumulation of iron in red blood cells. Iron supplementation is generally avoided unless specifically indicated and carefully managed, as excess iron can be harmful. In some cases, vitamin B6 (pyridoxine) supplementation may be tried, as it can improve hemoglobin production in certain types of sideroblastic anemia, though its effectiveness varies.
Management of ataxia focuses on supportive therapies to improve motor skills and quality of life. This includes physical therapy to improve balance, coordination, and gait, and occupational therapy to help with daily tasks affected by dysmetria and intention tremor. Speech therapy can address mild speech difficulties. Assistive devices, such as walkers or canes, may become necessary as the ataxia progresses to aid mobility and prevent falls.
This condition is inherited in an X-linked recessive pattern, meaning it primarily affects males. Females are typically carriers and usually do not show symptoms, or have very mild ones, because they have a second, healthy X chromosome. For a male with the condition, all his daughters will be carriers, and none of his sons will be affected. For a female carrier, there is a 50% chance with each pregnancy that her son will be affected and a 50% chance her daughter will be a carrier. Genetic counseling is recommended for families to understand these risks.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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