Allergy, Asthma, and Immunology

Severe Combined Immunodeficiency (SCID)

What is severe combined immunodeficiency (SCID)?

SCID is a group of very rare, life-threatening diseases that are present at birth. The disease causes the child to have very little or no immune system. As a result, the child's body is unable to fight off infections. This disease process is also known as the "boy in the bubble" syndrome, because living in the normal environment can prove fatal to these children.

Children with this rare, inherited disease become very ill with illnesses such as pneumonia, meningitis, and chickenpox and can die within the first year of their life. With new advances in treatments for these children, however, children with SCID can be successfully treated.

What causes SCID?

SCID is a group of inherited disorders. Many genetic defects can cause SCID. These defects reduce the ability of white cells in the blood to fight infection.

What are the symptoms of SCID?

Symptoms of SCID usually become apparent within the first year. The following are the most common symptoms of SCID. However, each child may experience symptoms differently. Symptoms may include:

• numerous, serious, and/or life-threatening infections that are not easily treated and do not respond to medications (as they would in children without SCID), including the following:
  
  
  • pneumonia - infection of the lungs.
  • meningitis - infection of the brain.
  • sepsis - infection in the bloodstream.
    
    
• other infections, including the following:
  
  
  • chronic skin infections
  • yeast infections in the mouth and diaper area
  • diarrhea
  • infection of the liver

How is SCID diagnosed?

A diagnosis of SCID is usually made based on a complete medical history and physical examination of your child. In addition, multiple blood tests may be ordered to help confirm the diagnosis.

Treatment for SCID:

• your child's age, overall health, and medical history
  
  
• extent of the disease
  
  
• your child's tolerance for specific medications, procedures, or therapies
  
  
• expectations for the course of the disease
  
  
• your opinion or preference

The best treatment for this disease is a bone marrow transplant (BMT), which, in most cases, would cure the problem. A bone marrow transplant involves taking cells that are normally found in the bone marrow (the soft, spongy tissue found inside the bones that is responsible for the development and storage of blood cells), and giving them back either to the patient or to another person. The goal of bone marrow transplantation is to infuse healthy bone marrow cells into a person after their own unhealthy bone marrow has been eliminated. BMT would help increase the sick child's immune system.

Other treatment options include giving the child injections to help boost the child's immune system, and treating each infection very promptly and accurately. In addition, researchers have had some success using gene therapy to treat SCID. However, gene therapy is still in the experimental stages.