Severe Combined Immunodeficiency: Causes, Symptoms & Treatment

Severe Combined Immunodeficiency: Causes, Symptoms & Treatment
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  • 0:01 Severe Combined…
  • 1:00 Causes of SCID
  • 2:08 Symptoms of SCID
  • 2:58 Treatments for SCID
  • 4:34 Lesson Summary
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Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Severe combined immunodeficiency is a genetic disorder that inhibits the body's ability to fight infections. This disorder affects children and results in increased susceptibility to infections. One possible treatment is a bone marrow transplant.

Severe Combined Immunodeficiency (SCID)

What would your life be like if you were born without an immune system? Your immune system is your body's way of fighting off things you cannot see, such as viruses, bacteria and fungi. With no defense against these microscopic organisms, you would have to live in a completely sterile environment. You couldn't risk being near someone who sneezed. You couldn't even shake hands with someone for fear of infection, let alone give someone a hug.

In children with severe combined immunodeficiency, or SCID , this nightmare is a reality. SCID is defined as a genetic disorder in which the body cannot fight infection due to a deficiency of B cells and T cells. Your B and T cells are two of the major weapons of your immune system. In fact, the word 'combined' in the term 'severe combined immunodeficiency' is included because both of these infection-fighting cells are severely deficient.

Causes of SCID

We mentioned that a person with a severely deficient immune system would need to live in a sterile environment as if they were in a bubble, cut off from the rest of the world. In fact, another name for severe combined immunodeficiency is 'bubble boy disease.' This nickname for the disease comes from the idea of living life in a sterile bubble as well as the fact that boys are more commonly affected.

The most common type of SCID is caused by a defect on the X-chromosome, which means it only affects males. Females might inherit one defective X chromosome, but because girls inherit a second X, the normal one covers up the defect, allowing the girl's immune system to function properly. Boys, on the other hand, inherit one X and one Y chromosome. So if they get the defective X, then they get the disease. There are other types of SCID that can affect girls. These types are caused by either a deficiency of an enzyme or other genetic defects, but these types are less common.

Symptoms of SCID

SCID is a rare but life-threatening condition that is seen in children. The children lack their natural defense against infection, so it's not hard to understand that the leading sign or symptom of SCID is increased susceptibility to infection. These infections can occur anywhere in the body from head to toe. This could include meningitis, which is an infection involving the coverings of the brain and spinal cord, recurrent ear infections, sinus infections, and thrush, which is an infection in the mouth. Additional infections include pneumonia, skin infections such as persistent diaper rash, and chronic diarrhea. These recurrent infections take a toll on the body, and the child may fail to grow or thrive.

Treatments for SCID

While SCID is a life-threatening condition, there are possible treatments available if it is detected early. If it is not detected, it is often fatal within a child's first few years of life.

When a child is diagnosed with SCID, the first goal of treatment for SCID is to control any current infections. Then, the focus turns to preventing more infections. This may involve the administration of antibiotics or intravenous immune globulins (IVIG) to aid the immune system.

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