DH+SCID


 * SCID**, Severe Combined Immunodeficiency, is a primary immune deficiency. The defining characteristic is usually a severe defect in both the T- & B-lymphocyte systems. This usually results in the onset of one or more serious infections within the first few months of life. These infections are usually serious, and may even be life threatening, they may include pneumonia, meningitis or bloodstream infections.

"This once-fatal disease should be now seen as a pediatric emergency, a condition that needs immediate diagnosis and treatment. says Dr. Rebecca Buckley, chief of Duke's division of pediatric allergy and immunology. "Early diagnosis of SCID is rare because doctors do not routinely perform a test in newborns to count white blood cells. Such a blood test could pick up children with SCID as well as those with other serious immune deficiencies that would not be apparent until the child developed an infection. A simple blood test could allow us to treat, and most likely cure, SCID in an infant at a reasonable cost. If found later, less effective treatment can run into the millions." Buckley states, "What we're saying is that essentially every baby with SCID could be cured if diagnosed early enough. SCID should be considered a pediatric emergency." 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). Other cases of SCID are caused by a variety of other defects.

SCID
Autosomal recessive inheritance – Autosomal recessive forms of SCID result when a child inherits two defective copies of the same autosomal gene. The parents in this case each carry one normal copy of the gene and one abnormal copy. In the case of an affected child, the child inherits both abnormal copies. One form of SCID is ADA deficiency. This condition results from the lack of an enzyme that helps cells to get rid of toxic byproducts. Without ADA, poisons build up and kill the lymphocytes. It was in 1972 that the ADA deficiency form of SCID was recognized, but ADA deficiency has an autosomal recessive inheritance pattern that affects males and females equally. It was known though that a predominance of SCID patients were male, leading researchers to suspect that an X-linked inheritance also existed. X-linked inheritance or X-SCID – A female can be a silent carrier of a defective X- chromosome, because her 2nd X chromosome compensates and consequently she is unaffected. A male who inherits the defective X chromosome, however, will be affected. X-linked SCID affects only males and accounts for approximately 45% of all cases of SCID. It wasn't until 1993 that Dr. Jennifer Puck and Dr. Warren Leonard simultaneously, but independently, discovere
 * SCID** or Severe Combine Immune Deficiency is the most severe of the Primary Immune Deficiency diseases. The defining characteristic of SCID is the absence of T cells and, as a result, lack of B cell function as well. Unless these defects are corrected the child will die of opportunistic infections before their first or second birthday. As of this writing, there are ten known forms of SCID. Often some of the combined immunodeficiencies are mislabeled as SCID. Consequently, what some call SCID are not listed in the table. Additionally, there are a number of cases of SCID for which the genetic cause is still undetermined. No matter what the form of SCID though, the end result is that critical immune defenses are missing and treatment should be considered a pediatric emergency.
 * Inheritance**