Adenosine Deaminase Severe Combined Immunodeficiency (ADA-SCID)

What Is Adenosine Deaminase Severe Combined Immunodeficiency (ADA-SCID)?

When you have a severe combined immunodeficiency (SCID), your immune system can't fight off even mild infections on its own.

With adenosine deaminase severe combined immunodeficiency (ADA-SCID), your body's defenses stop working because of a problem with your genes.

ADA-SCID is a serious disease that usually shows up early in life. Treatments can help, though, and people who get treatment before an infection happens can live long, healthy lives.

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Everyone has ADA genes. If you have ADA deficiency, you have a glitch (mutation) in yours. As a result, your body doesn't make enough of a certain tool, called an enzyme, that helps your white blood cells protect you from getting sick. Without that protection, you can easily get infections.

If your child is born with ADA deficiency, they'll probably get a SCID diagnosis by the time he’s 6 months old. If the disease starts later, the symptoms may be less severe.

With treatment, you can manage symptoms and avoid infections. Left untreated, the body becomes less and less able to fight infections, which can be life- threatening.


You get ADA-SCID only if both your parents pass on a copy of a faulty gene to you. If you get a copy from just one parent, you won't get the disorder, but you can pass that copy on to your own children.


Symptoms usually appear in the first months of life. If your baby has this disease, they may have a lot of infections in different parts of their body, including:

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It’s common for babies to get infections. Pay special attention if your child has them often and they:

  • Are severe
  • Are long-lasting
  • Are unusual
  • Frequently recur

Children with ADA-SCID often have diarrhea and widespread skin rashes. They may also grow slowly and have delayed progress in other development areas like motor and social skills.

If the disease doesn’t appear until later in childhood or adulthood, the symptoms may be mild at first. The first symptoms may be ear or upper- respiratory infections that keep coming back.

Getting a Diagnosis

Your chances of living well are best with early diagnosis and treatment.

Some states screen all newborns for ADA-SCID, and many experts say early testing should be required in all states. You can be checked at any age. A doctor will take a blood sample and test it to see if the immune system is working right.

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Sometimes the doctor needs to do more than one blood test to diagnose ADA-SCID.

Your doctor will want to know:

  • What kind of infections have you (or your child) had?
  • How long did they last?
  • Did they go away after treatment?
  • Did they come back?
  • Does anyone else in your family have immune system problems?
  • Has anyone in the family had genetic testing?

If you find out you or child has ADA-SCID, your doctor may talk with you about genetic counseling and early blood testing of all your children.


You'll want to start treatment right away. Find a specialist who treats immune deficiencies.

Your doctor will prescribe antibiotic, antifungal, or antiviral medications to treat any existing infections.

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Your doctor may also prescribe antibiotics to prevent new infections. A baby or child with ADA-SCID may need to spend some time in an isolated hospital room, but their parents will be able to be with them.

Although it doesn’t cure the disease, enzyme replacement therapy (ERT) may help your immune system work better and prevent infections. In this therapy, you get injections of healthy enzymes, usually from a cow.

The only way to cure ADA-SCID is with a stem cell transplant. Doctors will put healthy stem cells into your body to try to rebuild your immune system. It’s most successful in infants, and when the donor stem cells come from a close relative. In some cases, people need chemotherapy before getting a transplant to kill damaged cells first.

Scientists are looking for more ways to treat ADA-SCID. Studies using gene therapy show promise. In these studies, researchers add healthy genes to your own cells in a lab and transplant them back into your body to correct faulty cells.

Taking Care of Yourself or Your Child

If you or your child has ADA-SCID, avoid infections as much as you can. Wash your hands often, stay away from people who are sick, and talk to your doctor before getting any vaccinations. You shouldn't get any vaccines that are made with live viruses. These include rotavirus, MMR, chicken pox, and the flu vaccine that comes in mist form. (You can get other types of flu vaccines that don't have the live virus.)

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Take care of yourself. Eat right, exercise, and get enough sleep to help your body stay healthy.

Stay in close contact with your doctor and keep up with your checkups.

Get support. Other families living with the disease can help. Talk through your challenges, and get tips for making your daily life easier.

What to Expect

The key is how soon you start treatment. Without it, babies with ADA-SCID rarely live past their second birthdays. But those who get treatment before infections happen can live long, healthy lives.

Getting Support

To learn more about ADA-SCID, visit the web site of the Immune Deficiency Foundation. The site has links to help you connect with other families facing this condition.

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