How to use Scid in a sentence
Severe combined immunodeficiency (SCID) is the most serious primary or congenital human immunodeficiency disorder.
Children with SCID are vulnerable to recurrent severe infections, retarded growth, and early death.
In children with SCID, the immune system does not function properly because T, B, and NK cells are either absent or defective.
Several different immune system disorders are grouped under SCID.
Children with X-linked SCID have low T-cell and natural killer (NK) cell levels but elevated B-cell levels.Advertisement
In this form of SCID the lymphocyte or white blood evaluation is identical to X-linked SCID but is autosomal recessive and, therefore, occurs in girls and boys.
The rate of SCID is not perfectly documented.
In all forms of SCID, B and T cells are non-functioning.
They may or may not be present in various forms of SCID, but they are always non-functioning.
In some forms of SCID, NK cells are also absent or non-funtioning.Advertisement
For the first few months after birth, an infant with SCID is often protected by antibodies acquired before birth from the mother's blood.
As early as three months of age, however, the SCID child begins to suffer from mouth infections (thrush), chronic diarrhea, otitis media, and pulmonary infections, including pneumocystis pneumonia.
The first screening test for SCID is a white blood cell count with a count of the lymphocytes (differential) because in most forms of SCID the lymphocyte count will be very low.
If the numbers of all of these cell types are normal and SCID is still suspected, more specialized tests can be done to test the lymphocyte cell functions.
Rarely there are children with SCID who have normal lymphocyte numbers and nonfunctioning cells.Advertisement
Bone marrow transplants are as of 2004 regarded as one of the few effective standard treatments for most types of SCID.
As an example of gene therapy for SCID children with ADA deficiency, the child receives periodic infusions of his or her own T cells corrected with a gene for ADA that has been implanted in an activated virus.
Other types of SCID have been treated with gene therapy, but these procedures have been put on hold due to serious complications (malignancies).
Researchers are as of 2004 also investigating treating SCID in the yet unborn fetus, which has been done successfully a few times.
Genetic counseling is recommended for parents of a child with SCID who are considering having more children and for potential parents who have a family history of the disease and believe they may be carriers.Advertisement
Without prompt treatment SCID is nearly always fatal.
Research is continuing into in utero treatment options, and some in utero treatments have been successfully carried out, so fetal screening may be helpful if there is a possibility that the child has SCID.
Adenosine deaminase (ADA)-An enzyme that is lacking in a specific type of severe combined immunodeficiency disease (SCID).
For example, severe combined immunodeficiency disease (SCID) is caused by the defective development or function of these two types of lymphocytes.
If the deficiency is not treated (usually by bone marrow transplant), a person with SCID usually dies from infection before the age of two years.Advertisement
The most common form of SCID is X-linked, i.e. the defect is on the X chromosome and, therefore, occurs only in boys.
In the early 2000s new genetic defects leading to SCID are being identified each year.
For most patients with SCID, bone marrow transplantation is necessary.