Hyper-IgM syndrome type 3
Hyper-IgM syndrome type 3 is a form of hyper IgM syndrome characterized by mutations of the CD40 gene. In this type, Immature B cells cannot receive signal 2 from helper T cells which is necessary to mature into mature B cells.
Hyper IgM syndromes
Hyper IgM syndromes is a group of primary immune deficiency disorders characterized by defective CD40 signaling; via B cells affecting class switch recombination and somatic hypermutation. Immunoglobulin class switch recombination deficiencies are characterized by elevated serum IgM levels and a considerable deficiency in Immunoglobulins G, A and E. As a consequence, people with HIGM have an increased susceptibility to infections.Signs and symptoms
Hyper IgM syndrome can have the following syndromes:- Infection/Pneumocystis pneumonia, which is common in infants with hyper IgM syndrome, is a serious illness. PCP is one of the most frequent and severe opportunistic infections in people with weakened immune systems.
- Hepatitis
- Chronic diarrhea
- Hypothyroidism
- Neutropenia
- Arthritis
- Encephalopathy
Cause
Different genetic defects cause HIgM syndrome, the vast majority are inherited as an X-linked recessive genetic trait and most sufferers are male.IgM is the form of antibody that all B cells produce initially before they undergo class switching. Healthy B cells efficiently switch to other types of antibodies as needed to attack invading bacteria, viruses, and other pathogens. In people with hyper IgM syndromes, the B cells keep making IgM antibodies because can not switch to a different antibody. This results in an overproduction of IgM antibodies and an underproduction of IgA, IgG, and IgE.