Characterized by minimal or no immune response, Severe Combined Immunodeficiency (SCID), typifies a group of rare, sometimes fatal, congenital disorders. An abnormality in the specialized white blood cells (B- and T-lymphocytes) that protect us from being infected by viruses, bacteria, and fungi is the defining characteristic of SCID, also known as "bubble boy" disease. SCID patients can contract the same illnesses repeatedly, like pneumonia, meningitis, and chicken pox because they don’t have a functional immune system. Many die before reaching a year old if the disease isn’t identified quickly.
Although new treatments, such as bone marrow and stem cell transplants may save as many as 80% of SCID patients.

Nearly 50 percent of SCID cases are connected to the X chromosome, thus it only affects males, and is passed on by the female carrier, but all forms of SCID are hereditary. Apparently, the gene mutation results in the T-lymphocytes not developing properly, these are the specialized white blood cells made in the bone marrow to fight infection. This hinders the activating and regulating of other cells in the immune system. The results can be a severely compromised or completely lacking immune system in the affected child.

SCID usually isn’t diagnosed until six months of age for infants without a family history. During that amount of time, an infant has been able to build a history of recurrent infection, or been given a failure to thrive diagnosis because of repeated infections. The repeated infections, which are less responsive to treatment and more serious that expected, may be bacterial, viral, or fungal, and may be accompanied by chronic diarrhea. Some examples of recurrent infections are ear, skin and sinus infections, oral thrush, meningitis, and pneumonia.

Your child with this diagnosis may require long-term antibiotic therapy to help prevent infection, may need to wear a mask, and avoid crowds and sick people. Injecting a weakened live vaccine virus into a child with SCID can be dangerous because they lack the typical defense of antibodies to the viruses. Therefore, they should not receive the typical childhood immunizations like chickenpox (varicella) or measles, mumps, and rubella (MMR) which use live viruses. To assist the body in fighting infection doctors may also need to infuse the patient with intravenous immune globulin (IVIG).

Stem cell transplant is still the most effective treatment for SCID. New stem cells, found in bone marrow, are transplanted in hope that they will rebuild the immune system. Best results usually come from using the bone marrow of a sibling, if available, or a parent, within the first few months of life. Some children will require chemotherapy to destroy the cells in their bone marrow and make room for the donated cells and prevent their cells from attacking the donated cells. Infants with SCID may have to endure repeated hospital stays with painful procedures. Support during this time from family, friends, and support groups is invaluable.

Another treatment involves an enzyme being injected every week, for life, into a child with a type of SCID caused by a missing enzyme, instead of surgery. Gene therapy is also a promising treatment, which involves removing cells and replacing the defective genes with healthy genes and then surgically putting them back into the child. When the repaired cells find their way back to the bone marrow, they can reproduce healthy immune cells.

Read about David Vetta, the most famous patient of SCID and see numerous photos of him.