Severe Combined Immunodeficiency (SCID)

Also called: bubble boy disease

What is severe combined immunodeficiency?

Severe combined immunodeficiency (SCID) refers to a group of at least 10 inherited diseases that are already present at birth. People with SCID do not have immune cells that can protect them from infections. Normally, two types of immune cells, called T cells and B cells, protect the body from invading viruses, bacteria and fungi. In people with SCID, the T cells and B cells are missing or do not function correctly. People with SCID get infections easily because the immune system does not work properly.

How common is severe combined immunodeficiency?

SCID is diagnosed in one infant per 40,000 to 100,000 live births. That is a total of about 40 to 100 infants diagnosed with SCID in the United States each year.

What are the symptoms of severe combined immunodeficiency?

Symptoms of SCID in infants include the following:

  • More than the typical number of infections, such as:
    • Ear infections,
    • Pneumonia or bronchitis, and
    • Oral thrush (a type of yeast that creates white, sore areas in the mouth).
  • Chronic diarrhea
  • Child does not grow and gain weight as expected (failure to thrive)

How is severe combined immunodeficiency treated?

The most effective treatment for SCID is bone marrow transplant. Immune cells are formed in the bone marrow by bone marrow stem cells. A bone marrow transplant gives the patient with SCID new stem cells from a healthy donor’s bone marrow. Bone marrow stem cells can live for a long time. They keep working to make healthy immune cells to replace the patient’s missing or non-working immune cells.

A bone marrow transplant is most successful for curing SCID when the donor is “tissue matched” to the person with SCID. Every person has a tissue type, which is also called the HLA type. HLA stands for human leukocyte antigen. HLA is a marker your immune system uses to recognize which cells belong in your body and which do not. An ideal bone marrow donor has a matched HLA type with the person who has SCID. Sometimes, the patient’s sister or brother will be fully matched and can be the donor.

For patients without a fully matched sibling donor, bone marrow transplants from parents or unrelated matched donors are often done. Patients transplanted with cells from a parent or an unrelated donor do not do as well as those receiving fully matched transplants. For those patients without fully matched donors, researchers are working to devise better treatments, such as gene therapy.

St. Jude is trying to find better treatments for children with X-linked severe combined immunodeficiency disease (SCID-Xl). This disorder almost always occurs in boys and affects about one in 50,000 to 100,000 newborns. The St. Jude research study called LVXSCID-ND is looking at treating SCID-X1 with a new method called “gene therapy.” In this process, a corrected (normal) copy of the abnormal gene is transferred into the patient’s own bone marrow stem cells.

What are the survival rates for severe combined immunodeficiency?

Without treatment, children with SCID usually die from an infection within the first two years of life. With an early bone marrow transplant, careful monitoring by an experienced doctor and strong treatment for infections, survival rates are very good.

Why choose St. Jude for your child’s severe combined immunodeficiency treatment?

  • The St. Jude Bone Marrow Transplantation and Cellular Therapy Department is one of the largest pediatric programs of its kind in the world. We have performed more than 2,900 transplants since 1982.
  • The St. Jude Transplant Program is approved by the Children's Oncology Group (COG), the National Marrow Donor Program (NMDP), the Pediatric Blood and Marrow Transplant Consortium, and the Center for International Blood and Marrow Transplant Research (CIBMTR). The program is certified by the Foundation for Accreditation of Cellular Therapy (FACT).
  • Doctors in the St. Jude Transplant Program work closely with laboratory scientists to quickly move new discoveries to patient care. The program conducts clinical trials to study these new discoveries.
  • The Transplant Unit at St. Jude is dedicated to the care of patients receiving bone marrow transplants, stem cell transplants or cellular therapy. The transplant team includes doctors and nurse practitioners with extensive training and experience in this lifesaving treatment for SCID. The team also includes registered nurses, a pharmacist, clinical dietitian, child life specialist and social worker.
  • The 18-bed Transplant Unit is staffed around the clock by nurses who are trained in the care of patients with SCID. The standard nurse-to-patient ratio is 2:1.
  • Each patient room in the St. Jude Transplant Unit has an adjoining parent room that includes a bed, bath, television and phone, so parents can comfortably stay with their child at all times during the transplant process.
  • St. Jude has one of the leading gene therapy programs in the country and has a great deal of experience producing and using gene therapy vectors to treat blood and immune cell diseases.
  • St. Jude has experience performing transplants for SCID disorders. They also have an expert pediatric immunologist on staff, working with the transplant team.

What current clinical trials are open for severe combined immunodeficiency?

LVXSCID-ND: Gene Transfer for X-Linked Severe Combined Immunodeficiency (SCID) in Newly Diagnosed Infants

A Pilot Feasibility Study of Gene Transfer For X-Linked Severe Combined Immunodeficiency (SCID) in Newly Diagnosed Infants Using a Self-Inactivating Lentiviral Vector To Transduce Autologous CD34 + Hematopoietic Cells

Diseases Treated:

X-linked Severe Combined Immunodeficiency (SCID-X1)


  • Diagnosis of Severe Combined Immunodeficiency Disease, X-linked (SCID-X1)
  • Newborn to 2 years of age
  • No prior therapy with allogeneic stem cell transplantation
  • No HIV infection
View Trial

SCIDBMT: Bone Marrow Transplant for Infants with Severe Combined Immunodeficiency (SCID)

Haplocompatible Transplant Using TCRa/β Depletion Followed by CD45RA-Depleted Donor Lymphocyte Infusions for Severe Combined Immunodeficiency (SCID)

Diseases Treated:

Severe combined immunodeficiency (SCID)


  • Infant at least 2 months old with severe combined immunodeficiency (SCID)
  • Has suitable matched sibling donor or matched unrelated donor or a single haplotype matched family member donor
View Trial