Severe combined immunodeficiency (SCID), also known as "bubble boy disease", is a genetic disorder where the immune system is impaired or absent. It affects both B cells and T cells. SCID can be diagnosed through newborn screening and symptoms include life-threatening infections in the first months of life. Treatment options include preventing infections, enzyme therapy for some types of SCID, gene therapy, and bone marrow transplantation which has been successful using matched or half-matched donors. The original "bubble boy" David Vetter died after transplantation due to an unscreened virus in his donor marrow.

1. Severe Combined
Immunodeficiency
(bubble boy disease)

2. Contents
 Introduction
 Types of SCID Symptoms
 Diagnosis of SCID
 Treatment for SCID
 Transplant for SCID

3. Introduction
 Severe combined immunodeficiency (SCID), is a genetic disorder in which both
"arms" (B cells and T cells) of the adaptive immune system are impaired due
to a defect in one of several possible genes.
 SCID is a severe form of heritable immunodeficiency.
 It is also known as the bubble boy disease because its victims are extremely
vulnerable to infectious diseases and some of them, such as David Vetter,
become famous for living in a sterile environment.
 SCID is the result of an immune system so highly compromised that it is
considered almost absent

4. Types of SCID
 X-linked severe combined immunodeficiency.
 Adenosine deaminase deficiency.
 Omenn syndrome
 Bare lymphocyte syndrome

5. Symptoms and diagnosis of SCID
 Children with SCID are at risk for life-threatening infections. From their first
months of life, they have infections that may be frequent, severe, long-
lasting or hard to treat. Infections may occur in the lungs (pneumonia),
around the brain and spinal cord (meningitis) or in the blood stream.
 Several US states are performing pilot studies to diagnose SCID in new-borns
through the use of T-cell recombinant excision circles.
 The delay in detection is because new-borns carry their mother's antibodies
for the first few weeks of life and SCID babies look normal.

6. Treatment for SCID
 Preventing infections
 Enzyme therapy for ADA deficiency SCID
The standard treatment for ADA deficiency SCID is treatment with a form of
the ADA enzyme called PEG-ADA. Treatment with PEGADA is effective in
about 90% of children. However, despite PEGADA therapy, some children
continue to require IVIG treatments
 Gene therapy
A treatment option being studied in clinical trials is gene therapy. Gene
therapy has shown promising results for some patients with ADA deficiency
SCID. At first, gene therapy also appeared to be a promising treatment for X-
linked SCID, but some children treated with gene therapy developed
leukemia. New trials of gene therapy are in progress. But despite some
promising results, gene therapy remains an experimental treatment for SCID.

8. Transplant for SCID
 The most common treatment for SCID is bone marrow transplantation, which has
been successful using either a matched related or unrelated donor, or a half-
matched donor, who would be either parent.
 The half-matched type of transplant is called haploidentical and was perfected by
Memorial Sloan Kettering Cancer Center in New York and also Duke University
Medical Center which currently does the highest number of these transplants of
any center in the world.
 Haploidentical bone marrow transplants require the donor marrow to be depleted
of all mature T cells to avoid the occurrence of graftversus-host disease (GVHD).
 Consequently, a functional immune system takes longer to develop in a patient
who receives a haploidentical bone marrow transplant compared to a patient
receiving a matched transplant.
 David Vetter, the original "bubble boy", had one of the first transplantations but
eventually died because of an unscreened virus, Epstein-Barr (tests were not
available at the time), in his newly transplanted bone marrow from his sister.

9. Conclusion

10. THANK YOU
SUBHADEEP ADITYA
BSC BIOTECHNOLOGY
UG/BSBIOT/08/2017/037