What causes Common variable immunodeficiency ?
What causes common variable immunodeficiency (CVID)? Common variable immunodeficiency (CVID) is usually sporadic and thought to result from a combination of genetic and environmental factors. In most cases, the exact cause of CVID is unknown. Genetic factors associated with CVID include mutations in genes involved in the development and function of immune system cells (B cells) which help protect against infection. B cells make proteins called antibodies (also known as immunoglobulins), which attach to foreign agents and "mark" them to be destroyed. Mutations in genes associated with CVID result in B cells that don't make enough antibodies. This causes difficulty fighting infections, causing the signs and symptoms of CVID. Mutations in at least 10 genes have been associated with CVID. About 10% of affected people have mutations in the TNFRSF13B gene. However, not all people who inherit a mutation associated with CVID develop the disease. This is why additional genetic and/or environmental factors are probably needed for the disorder to occur. While CVID usually occurs in people with no family history of the condition, some cases are inherited in an autosomal dominant or autosomal recessive manner.