Severe Combined Immunodeficiency (SCID)

What is severe combined immunodeficiency (SCID)?

Patients with severe combined immunodeficiency (SCID) are born without a functioning immune system and therefore are at increased risk of infections and death before the age of 2. A variety of genetic defects can produce SCID.

What are the symptoms of SCID, and how is it diagnosed?

Symptoms include diarrhea, fungal infections, and poor physical growth. In the past, patients were diagnosed based on their clinical presentation or family history. Now, your child may have been diagnosed based on a newborn screening before he or she developed any infections. Patients with SCID are categorized by their primary genetic defect, but common to all forms of SCID is an absence of protective T and B cells (immune cells that help attack invaders like bacteria, viruses, and fungi). Your child’s diagnosis will be confirmed by genetic testing and an assessment of your child’s T and B cell numbers and function.

How is SCID treated at Stanford Medicine Children’s Health?

The only curative therapy for SCID is stem cell transplantation from a healthy individual or with the patient’s own genetically modified cells, also known as gene therapy.

The therapy of choice for most patients with SCID is stem cell transplantation from a healthy matched donor, usually a sibling. If a healthy matched sibling donor is not available, then stem cell transplantation from a half-matched, or haploidentical, family donor, usually the mother, is the next-best option. In the past, using a mismatched donor could increase the chances of developing graft-versus-host disease (GVHD). Stanford doctors can now deplete T cells that cause graft-versus-host disease from the stem cell graft before transplantation, reducing the risk of GVHD and enabling every patient to find a donor. If no family member is a suitable donor, a matched unrelated donor can be used.

It usually takes four to six weeks after transplantation for your child to develop adequate immune function to protect them from infections so that they can be discharged from the hospital.

Why choose Stanford Medicine Children’s Health for SCID treatment?

We are working to make stem cell transplants safer and accessible to every patient with SCID. Stanford’s Alice Bertaina, MD, PhD, is an internationally renowned expert in depleting T cells from a mismatched stem cell graft to reduce GVHD. This technique has been shown to significantly reduce the risk of GVHD to the level seen in fully matched donors, while also reducing other posttransplant complications. This means that every patient with SCID can now find a suitable stem cell donor. Dr. Bertaina has performed more than 400 transplants using this approach.

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We are also working to make stem cell transplantation safer for patients with SCID by eliminating the need for chemotherapy before transplant. In a clinical trial, patients receive an antibody before their stem cell transplant to make space for the normal stem cells to grow, without the need for chemotherapy.