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Genetic and Rare Diseases Information Center (GARD)

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Severe combined immunodeficiency

Other Names for this Disease
  • Bubble boy disease
  • SCID
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Your Question

My baby has low CD3 and CD4 cells. I have consulted a hematologist and was told it is doubtful my baby has SCID. When can we consider it is SCID?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is severe combined immunodeficiency?

Severe combined immunodeficiencies (SCID) are inherited immune system disorders characterized by defects in both T cells and B cells. SCID causes a high susceptibility to life-threatening infections and failure to thrive. Without treatment, people with SCID do not tend to live past early childhood. Two common types of SCID include: 

Last updated: 8/10/2011

How is severe combined immunodeficiency (SCID) diagnosed?

A diagnosis of severe combined immunodeficiency (SCID) may be suspected if a baby shows any of the following persistent symptoms within the first year of life:[1]

Eight or more ear infections
Two or more cases of pneumonia
Infections that do not resolve with antibiotic treatment for two or more months
Failure to gain weight or grow normally
Infections that require intravenous antibiotic treatment
Deep-seated infections, such as pneumonia that affects an entire lung or an abscess in the liver
Persistent thrush in the mouth or throat
A family history of immune deficiency or infant deaths due to infections

Diagnosis can be confirmed by blood tests. Blood tests show significantly lower-than-normal levels of T cells and antibodies.[1]  

For further details on diagnosis see the following Web pages:

The Primary Immunodeficiency Resource Center provides further details regarding diagnosis of SCID. Click on the embedded link to view the page.

An article from eMedicine Journal provides detailed information on the diagnosis of SCID. Click on eMedicine Journal to view the page. You may need to register to view the article, but registration is free.

Last updated: 8/10/2011

  • Learning about severe combined immunodeficiency (SCID). National Human Genome Research Institute. July 2010; Accessed 8/9/2011.