The immune system is made up of cells in the body that protect a person from sickness. A child with SCID doesn’t have that protection. Illnesses like the flu or even the common cold can make a child with SCID extremely sick and could even be fatal.
SCID is not contagious and it cannot be passed from one person to another through germs.
SCID is caused by mistakes in the genes. Genes are found in cells and they give instructions to cells about how to function. In the case of SCID, the genes responsible for telling immune system cells how to work are faulty.
As a result, the baby does not produce important immune system cells called T cells. Because the T cells aren’t working properly, other important immune system cells such as B cells also don’t work like they should. Some babies are also missing immune cells called natural killer or NK cells.
All of the immune system cells are found in the bone marrow. T cells come from bone marrow cells that mature in an organ called the thymus.
SCID is rare. About 1 out of 58,000 children each year are diagnosed with SCID. That’s about 76 cases of SCID diagnosed annually in the United States.
SCID can affect any infant, regardless of race, gender, ethnicity, or socioeconomic status. It is, however, more common in certain communities, such as the Navajo Nation and the Amish and Mennonite communities.
Though a child with SCID might appear healthy at birth, the child is extremely vulnerable to germs. If child is exposed to viruses, bacteria or fungi, he or she will likely grow ill while attempting to fight the infection without a complete immune system.
Symptoms of SCID include:
- Failure to gain weight and grow at a healthy rate
- Life-threatening infections that don’t get better with medicine, such as brain, lung and blood infections
- Ear and sinus infections
- Skin rashes and infections
- Yeast infections in the mouth and the diaper area
- Liver infections
SCID is a life-threatening disease and must be diagnosed and treated promptly. If not treated, a child with SCID will not survive after the first year or two of life.