Iron-refractory iron deficiency anemia

Other Names: IRIDA; IRIDA syndrome; Anemia, hypochromic microcytic, with defect in iron metabolism; Iron-handling disorder, hereditary; Pseudo-iron-deficiency anemia

Iron-refractory iron deficiency anemia (IRIDA) is a type of iron deficiency anemia that typically does not improve with oral iron treatment. Children with IRIDA have too little iron in their blood, which causes their red blood cells to be small (microcytic) and pale (hypochromic). The anemia tends to be mild to moderate, but without enough healthy red blood cells, different parts of the body do not get enough oxygen

Epidemiology

Although iron deficiency anemia is relatively common, the prevalence of the iron-refractory form of the disease is unknown. At least 50 cases have been described in the medical literature. Researchers suspect that iron-refractory iron deficiency anemia is underdiagnosed because affected individuals with very mild symptoms may never come to medical attention.

Cause

Mutations in the TMPRSS6 gene cause iron-refractory iron deficiency anemia. This gene provides instructions for making a protein called matriptase-2, which helps regulate iron levels in the body. TMPRSS6 gene mutations reduce or eliminate functional matriptase-2, which disrupts iron regulation and leads to a shortage of iron in the bloodstream. Iron is an essential component of hemoglobin, which is the molecule in red blood cells that carries oxygen. When not enough iron is available in the bloodstream, less hemoglobin is produced, causing red blood cells to be abnormally small and pale. The abnormal cells cannot carry oxygen effectively to the body's cells and tissues, which leads to fatigue, weakness, and other symptoms of anemia.

Inheritance

Autosomal recessive inheritance, a 25% chance

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Symptoms

The symptoms of iron-refractory iron deficiency anemia can include tiredness (fatigue), weakness, pale skin, and other complications. These symptoms are most pronounced during childhood, although they tend to be mild. Affected individuals usually have normal growth and development.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Abnormal intestine morphology(Abnormality of the intestine)
• Hyperkeratosis
• Ichthyosis
• Intellectual disability(Mental deficiency)
• Pallor
• Peripheral neuropathy

30%-79% of people have these symptoms

• Decreased circulating copper concentration(Copper deficiency)
• Intrahepatic cholestasis

Diagnosis

Different types of iron tests include:

• Serum iron test, which measures the amount of iron in the blood
• Transferrin test, which measures transferrin, a protein that moves iron throughout the body
• Total iron-binding capacity (TIBC), which measures how well iron attaches to transferrin and other proteins in the blood
• Ferritin blood test, which measures how much iron is stored in the body
• Some or all of these tests are often ordered at the same time.

IRIDA is usually suspected in childhood due to the results of routine blood tests, but the diagnosis is confirmed by genetic testing.

Treatment

Children with iron-refractory iron deficiency anemia (IRIDA) usually do not respond to oral iron therapy. However, some children with IRIDA may partially respond to high doses of oral iron, prolonged oral iron therapy, or oral iron therapy combined with vitamin C. Medical researchers suggest the different responses to iron therapies may be linked to the exact change or mutation in the TMPRSS6 gene causing IRIDA.

Current treatment guidelines recommend an initial trial of oral iron along with vitamin C for several weeks to see if the anemia improves. If there is no improvement or minimal improvement, further treatment involves intravenous(IV) iron therapy. Even with IV therapy, only a partial improvement is expected. However in most cases, partial improvement of mild to moderate anemia results in enough healthy red blood cells to provide all of the body with oxygen.In addition, although only a few people with IRIDA have been followed into adulthood, red blood cell levels have been found to increase to low normal levels, suggesting treatment of adults with IRIDA may not be needed.

Prognosis

Children with IRIDA typically have normal growth and development.While information regarding the long-term effects of IRIDA are limited, in general, signs and symptoms of IRIDA appear to improve with age.

NIH genetic and rare disease info

• NIH info on Iron-refractory iron deficiency anemia

Iron-refractory iron deficiency anemia is a rare disease.

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