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Aase Syndrome

What Is Aase Syndrome?

Aase syndrome is a condition characterized by several birth defects. For a child to be diagnosed with Aase syndrome, he or she must have a reduced number of red blood cells from birth and three bones in one or both thumbs, instead of two. Some children may have additional deformities.

This condition is also called Aase-Smith syndrome and congenital anemia thriphalangeal thumb syndrome. Aase syndrome is an extremely rare condition. The AARP states that only 24 cases of Aase syndrome have been documented in medical literature (AARP, 2002).

What Causes Aase Syndrome?

The cause of Aase syndrome is unknown. However, experts believe that the condition may be hereditary (passed down through families). This is due to an occurrence of similar defects in siblings of children with Aase syndrome.

Aase syndrome is autosomal recessive, which means the condition is passed to a child through a defective gene from both parents. The parents may be unaffected by the condition if they only carry one defective gene and a normal copy of the same gene. According to the AARP, there is a one in four chance that each child born to parents with the defective gene will be born with Aase syndrome (AARP, 2002).

However, some children are born with the condition whose parents don’t carry the gene.

The anemia experienced by children with Aase syndrome is due to an underdevelopment of bone marrow. This causes the bone marrow to produce a lower-than-normal number of red blood cells.

What Are the Symptoms of Aase Syndrome?

Children who have Aase syndrome may display:

  • narrow shoulders
  • underdeveloped lower arms
  • cleft lip
  • cleft palate
  • heart defect (most commonly a ventricular septal defect, which is a hole between the lower heart chambers)
  • late closure of fontanelles (soft spots in the skull)
  • pale skin
  • inability to extend joints fully
  • droopy eyelids
  • deformed ears
  • small knuckles or no knuckles
  • reduced number of skin creases at the finger joints

Some children may have symptoms of anemia, such as fatigue and weakness.

How Is Aase Syndrome Diagnosed?

Your child’s pediatrician will first perform a physical examination to look for signs of Aase syndrome. If bone deformities are present, he or she may order an X-ray to view the bones in detail. If two or more defects are present, the doctor will draw a blood sample to check the complete blood count. This test will reveal if the child has a low number of red blood cells.

Next, an echocardiogram, which uses high-pitched sound waves, may be used to create a moving image of the heart. This test can indicate if any defect is present. The doctor may also want to observe how your child’s bone marrow is functioning. A bone marrow biopsy is used for this purpose. During a bone marrow biopsy, the doctor removes a small sample of bone marrow from your child’s bone using a long needle. The bone marrow is the spongy matter inside the bone that produces blood cells.

How Is Aase Syndrome Treated?

Aase syndrome is not curable, but it is treatable. As a first course of treatment, the pediatrician may prescribe your child steroid medication. This medication is often used to treat anemia in children with Aase syndrome.

Blood transfusions are another option for treating anemia in children with Aase syndrome. During a blood transfusion, donor blood is given to your child through an intravenous (IV) line. A child with Aase syndrome may need to receive several blood transfusions throughout the first year of his or her life.

If these treatments are not an option, a bone marrow transplant may be performed. A bone marrow transplant is used to replace damaged bone marrow with healthy bone marrow stem cells. This treatment option may be used to correct the way your child’s bone marrow produces blood cells. This will help to improve anemia.

Outlook for Aase Syndrome

Although the deformities present with Aase syndrome remain, the anemia gets better with age.

Complications of Aase Syndrome

Children with severe Aase syndrome may die early, or before birth. Children with this condition may also develop complications due to anemia.

These complications include:

  • weakness
  • fatigue
  • decreased oxygen in the blood

Other complications may arise in children with heart defects. These complications vary widely. Early treatment is one way of preventing complications.

Preventing Aase Syndrome

There isn’t a definitive way to prevent your child from getting Aase syndrome. However, genetic counseling may help to check for the defective gene in you and your partner.

Content licensed from:

Written by: April Kahn
Medically reviewed on: Jun 25, 2012: Brenda B. Spriggs, MD, MPH, FACP

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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