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What is severe combined immunodeficiency (SCID)?

SCID is a group of inherited immune system disorders. The immune system helps the body fight infections. In these disorders, parts of the immune system are missing or don’t work well. Babies born with SCID have many severe infections that keep coming back even after treatment. Babies with SCID have a hard time gaining weight or growing at a healthy rate.

The 2 most common types of SCID are:

  1. Classical X-linked SCID – This is sometimes called “bubble boy” disease. Only boys can have this type of SCID.
  2.  ADA deficiency SCID – Children with this type of SCID have low levels of an infection-fighting molecule called ADA. Boys and girls can have this type of SCID. This type of SCID may not cause problems until later in childhood, adolescence or even adulthood.

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How does blood or marrow transplant (BMT) work for SCID?

BMT, also known as a bone marrow transplant or blood stem cell transplant, is the only known cure for SCID. It replaces the unhealthy immune system with a healthy one.

Allogeneic transplant is used for SCID. This type of transplant uses healthy, blood-forming cells (stem cells) donated by someone else to replace the unhealthy ones. These healthy cells can come from a family member, unrelated donor or umbilical cord blood. The cells create the immune system. First, the child gets chemotherapy (chemo) to kill any unhealthy cells. Then, the healthy, donated cells are given to your child through an intravenous (IV) catheter. The new cells travel to the inside of the bones and begin to make healthy cells.

The entire transplant process, from the start of chemo until hospital discharge, can last weeks to months. This is followed by many months of recovery near the transplant center and at home. The transplant team will closely watch your child to prevent and treat complications.

When should my child see a transplant doctor?

Most children have a better chance of a cure if they have a transplant soon after diagnosis. Your child should see a transplant doctor as soon as your child is diagnosed.

Your child’s first appointment with a transplant doctor

At the first appointment, the transplant doctor will:

  • Review your child’s medical history
  • Talk with you about your child’s treatment options
  • Discuss the risks and benefits of transplant
  • Recommend the best time for your child to get a transplant and prepare for treatment
  • Start a donor search

Questions to ask your doctor

Ask questions so you understand your treatment options and can make decisions that are best for your child. Questions you may want to ask include:

  • What are my child’s chances of a cure with transplant? Without transplant?
  • What are the possible side effects of transplant? How can they be reduced?
  • How might my child’s quality of life change over time, with or without transplant?

 Learn more about planning for transplant

Most recent medical review completed March 2017.