8 factor deficiency of complement (Complement component deficiency 8) - Genes C8A or C8B.
Deficiency complement factor 8 is a disorder characterized by a malfunction of the immune system, which causes a form of immunodeficiency. People deficient complement factor 8 have a significantly increased risk of recurrent bacterial infections, especially Neisseria meningitidis. Although meningitis can be fatal, people with deficiency complement factor 8 are less likely to die from the infection than people in the general population who get it . The intensity factor deficiency 8 complement varies widely among affected individuals. While some people affected have one or more infections, others do not have any health problems related to the disturbance.
They described two types of deficiency 8 complement factor, designated as types I and II, classified by their genetic cause. Both types generate the same signs and symptoms.
Factor deficiency 8 complement is due to mutations in genes C8A, located on the short arm of chromosome 1 (1p32), or C8B gene, located on the short arm of chromosome 1 (1p32.2). The C8A genetic mutations result in deficiency type I, while mutations in the gene give rise to C8B type II. These genes, encoding units of a complex called complement component 8. This complex is composed of an alpha subunit encoded C8A gene, a beta subunit encoded by the gene C8B, and a gamma subunit encoded from the C8G gene. Complement component 8 participates in a part of the response of the complement system. The complement system is a group of proteins that act together against foreign invaders, triggering inflammation and removing cell debris and tissue. Complement component 8 interacts with several proteins of the complement system to form the membrane attack complex (MAC), which is inserted into the outer membrane of bacterial cells. This complex creates a pore in the membrane, which would damage the bacteria.
They have identified at least two mutations in the gene responsible C8A factor deficiency 8 complement type I and several mutations in the gene C8B, responsible factor deficiency type II 8 complement. Mutations in any of these genes lead to a deficiency of the respective subunit, which hinders the formation of complement component 8. Without complement component 8 can not be complexes membrane attack, which impairs the immune response, particularly against Neisseria meningitidis. This impaired immune response causes affected individuals have a tendency to recurrent episodes of meningitis.
This disease is inherited in an autosomal recessive pattern, that is, 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 deficiency of factor 8 complement, by complete PCR amplification of the exons of C8A and C8B genes, respectively, 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).