What Is SCID?
SCID also known as alymphocytosis, Glanzmann–Riniker syndrome, severe mixed immunodeficiency syndrome, and thymic alymphoplasia, is a group of inherited disorders that cause severe abnormalities of the immune system. These disorders lead to reduced or malfunctioning T- and B-lymphocytes, the specialized white blood cells made in the bone marrow and the thymus gland to fight infection. When the immune system doesn’t function properly, it can be difficult or impossible for it to battle viruses, bacteria, and fungi that cause infections.
SCID is called “combined” immunodeficiency because it affects the function of two kinds of infection-fighting cells. There are 14 forms of SCID. The most common type is caused by a problem in a gene found on the X chromosome and affects only males. Females may be carriers of the condition, but because they also inherit a normal X chromosome, their immune systems can fight infections normally. Males, on the other hand, only have one X chromosome, so if the gene is abnormal the disease appears.
Another form of SCID is caused by a deficiency of an enzyme (adenosine deaminase or ADA), which is necessary for lymphocytes to develop. Other cases of SCID are caused by a variety of other genetic defects.
Bubble Boy Disease
SCID is often called “bubble boy disease”. SCID became widely known during the 1970’s and 80’s, when the world learned of David Vetter, a boy with X-linked SCID, who lived for 12 years in a plastic, germ-free bubble.
There are several forms of SCID. The most common type is linked to the X-chromosome, making this form affect only males. Other forms of SCID usually follow an autosomal recessive inheritance pattern or are the result of spontaneous mutations. One of these other forms is linked to a deficiency of the enzyme adenosine deaminase (ADA) while other cases of SCID are caused by a variety of other defects.
How Is It Diagnosed?
Early diagnosis of SCID is usually difficult due to the need for advanced screening techniques. Several symptoms may indicate a possibility of SCID in a child, such as a family history of infant death, chronic coughs, hyperinflated lungs, and persistent infections. A full blood lymphocyte count is often considered a reliable manner of diagnosing SCID, but higher lymphocyte counts in childhood may influence results. Clinical diagnosis based on genetic defects is also a possible diagnostic procedure that has been implemented in the UK.
How Is It Treated?
The curative treatment, according to findings is bone marrow transplant. SCID is a pediatric emergency. When a child is diagnosed with SCID, a referral typically is made to a doctor who specializes in treating immune deficiencies — usually a pediatric immunologist or pediatric infectious disease expert.
It’s important to prevent infections in babies with SCID, so doctors may prescribe antibiotics to prevent infection and admit the child to an isolation room in the hospital.
Children with SCID cannot be immunized with live viruses — like the chickenpox (varicella) or measles, mumps, and rubella (MMR) vaccines. Because they lack the normal defense of antibodies to the viruses, introducing a virus to a child with SCID, even a weakened vaccine virus, can be dangerous. Children with SCID can only receive blood transfusions with blood that has been irradiated to kill white blood cells, because live white cells might attack the body.
Doctors may also administer an infusion of intravenous immune globulin (IVIG) to help the body fight infection.
When To Call A Doctor?
If you’re concerned that your child has more frequent infections than usual, discuss the possibility of immune deficiency with your doctor. If your child has a serious infection, contact your doctor immediately.