Severe Combined Immunodeficiency (SCID)

SCID is a rare inherited primary immunodeficiency disorder that appears during infancy. The immune system is composed of white blood cells of which half are T cells. These T cells play a vital role in fighting infection. They also assist another type of white blood cell known as B cells to produce antibodies (or immunoglobulins). These T and B cells do not function properly in individuals with SCID. In many cases, the affected individual is born with no T cells at all. Without T cells the B cells cannot make antibodies. In other words, these babies born with SCID become very sick very easily. The disease is lethal without early diagnosis and treatment.This is also known as the "boy in the bubble" syndrome, because living in the normal environment can prove fatal.

Signs & Symptoms:

  • Recurrent, severe respiratory infections
  • meningitis
  • sepsis
  • chronic skin infections
  • yeast infections in the mouth and diaper area
  • infection of the liver

Who is affected?

In Australia, it is thought to affect less than ten children born every year.


Treatments involve directly treating the infection with appropriate antibiotics and depending on the precise cause of SCID there are three main treatment options. If the cause is found to be due to a deficiency in the enzyme adenosine deaminase, then treatment involves replacing the missing enzyme through injections. If it is due to missing antibodies/immunoglobulins then these can be replaced through regular immunoglobulin replacement therapy. However, if the T cells are affected the only treatment is for a bone marrow transplant. In these cases there is a 100% mortality rate in the first year of life without a bone marrow transplant. Even after a transplant the mortality rate is 42% (de Pagter, 2015).


de Pagter, AP, Bredius, RG, Kuijpers, TW, Tramper, J, van der Burg, M, van Montfrans, J, Driessen, GJ, Dutch Working Party for Immunodeficiences, 2015, 'Overview of 15-year severe combined immunodeficiency in the Netherlands: towards newboard blood spot screening', European Journal of Pediatrics, 174(9): 1183-8.

Pai , S.-Y., et al. 2014, 'Transplantation Outcomes for Severe Combined Immunodeficiency, 2000–2009.' New England Journal of Medicine, 371(5): 434-446.

Information on this page is not intended to replace medical advice and any questions regarding a medical diagnosis or treatment should be directed to a medical practitioner.