Cause SCID is caused by deficiencies of various enzymes - proteins that promote specific chemical reactions in living cells. When the right enzymes are not present, the chemical reactions may not take place, and the cells may be damaged or prevented from functioning. These are the enzymes that produce the chemicals of the immune system. The enzyme deficiencies are in turn caused by abnormalities in genes. Incidence SCID is extremely rare, with no more than about 100 cases worldwide.
Cases are so dramatic, however, that the victims often become well known.
Symptoms you are likely to notice A small child suffers from repeated, serious infections. Symptoms a doctor may observe A test of blood cells reveals an absence of enzyme activity. Sometimes the infections that result from SCID can be controlled with antibiotics or with replacement antibodies called immunoglobulins. If these fail and the child's life is in danger, the standard treatment is a bone marrow transplant. The child's own bone marrow, which generates the abnormal immune cells, is destroyed.