Severe combined immunodeficiency , X - linked (X-linked severe combined immunodeficiency) - IL2RG gene

Severe combined immunodeficiency , X - linked (SCID) is an inherited immune system disorder that occurs almost exclusively in males. Affected children are prone to recurrent and persistent caused by certain bacteria, viruses and fungal infections. These infections are usually caused by opportunistic organisms that usually do not cause disease in people with normal immune systems. However, in individuals affected these organisms cause serious or potentially fatal diseases. Many newborns have chronic diarrhea and skin rashes, and grow more slowly than other children. Without treatment, affected males usually do not live beyond infancy.

This process is due to changes in the IL2RG gene (Interleukin 2 receptor gamma subunit), located on the long arm of the X chromosome (Xq13.1). This gene encodes a protein called the common gamma chain. This protein is a component of several different receptors that are involved in immune system function. The receptors are found in the cell membrane, with one end on the outside of the cell and the other end inside to transmit signals to the nucleus. Other proteins to bind these receptors to trigger a series of chemical reactions inside the cell. Receptors containing the common gamma chain lie on the surface of immature hematopoietic cells in the bone marrow. They associate with other proteins to direct cells to form hematopoietic cells. Receptors also regulate the growth and maturation of several subtypes of lymphocytes: T cells, B cells and natural killer cells (NK: Natural killer).

There are more than 300 mutations in the gene IL2RG people with severe combined immunodeficiency , X - linked (SCID). Most of these mutations involve changes in one or a few nucleotides in the gene. These changes result in the synthesis of a nonfunctional version of the common gamma chain or inhibit the synthesis of any protein. Without the common gamma chain, important chemical signals are not transmitted to the nucleus and cells can not develop normally. Functional deficiency mature lymphocytes prevents the immune system to fight infections.

Severe combined immunodeficiency , X - linked inherited recessive pattern with an X - linked In males, an altered copy of the gene in each cell is sufficient to express the disease. In women, the mutation would have to happen in both copies of the gene to express the disease. Because it is unlikely that women have two altered copies of this gene, males are affected by X - linked recessive disorders much more frequently than women. A feature of the X - linked inheritance is that fathers can not pass X - linked traits to their sons chromosome.

Tests in IVAMI: in IVAMI perform detection of mutations associated with severe combined immunodeficiency , X - linked, by complete PCR amplification of exons IL2RG gene, and subsequent sequencing.


Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).