MyD88 deficiency (MyD88 deficiency) - Gen MYD88.

MyD88 deficiency is a hereditary disorder of the immune system. This primary immunodeficiency affects the innate immune response to pathogens, which predisposes to abnormally frequent and severe by a subset of pyogenic bacteria infections. However, affected individuals have normal resistance to other common bacteria, viruses, fungi and parasites. The most common infections in MyD88 deficiency are caused by Streptococcus pneumoniae, Staphylococcus aureus and Pseudomonas aeruginosa. Most affected people have their first bacterial infection before 2 years of age, and infections can be life - threatening in infancy and childhood. Infections are less frequent from 10 years of age.

The MyD88 deficient children develop invasive bacterial infections, which may involve septicemia, meningitis, or joints, such as inflammation and arthritis. Invasive infections can also cause areas of tissue breakdown and the development of abscesses in internal organs. In addition, affected individuals can be localized infections in the ears, nose or throat. Although fever is a common reaction to bacterial infections, many people with MyD88 deficiency do not develop at first a high fever in response to these infections, even if the infection is severe.

MyD88 deficiency is due to mutations in the gene MYD88, located on the short arm of chromosome 3 (3p22). This gene encodes a protein involved in signaling within the immune cells. The protein acts as a MyD88 adapter protein connection receiving signals from outside the cell to proteins that transmit signals within the cell. In particular, signals transferred MyD88 Toll - like receptors and interleukin-1 (IL-1), which are important for rapid immune response to foreign invaders such as bacteria. In response to signals from these receptors, it stimulates MyD88 adapter protein signaling molecules that become the nuclear factor kappa-B. The nuclear factor kappa-B regulates the activity of multiple genes, including genes that control the body 's immune response and inflammatory reactions. It also protects cells from certain signals that would otherwise lead to apoptosis.

They have identified at least 4 MYD88 mutations in the gene in people with MyD88 deficiency. These mutations inhibit protein coding or coding lead to a nonfunctional protein. As a result, the protein can not relay signals that stimulate an immune response, which allows the development of multiple severe infections.

This disease is inherited in an autosomal recessive pattern, which means that both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with MyD88 deficiency, by complete PCR amplification of the gene exons MYD88, 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).