Common variable immune deficiency (CVID) is a disorder that impairs the immune system. People with CVID are highly susceptible to infection from foreign invaders such as bacteria, or more rarely, viruses and often develop recurrent infections, particularly in the lungs, sinuses, and ears. Pneumonia is common in people with CVID. Over time, recurrent infections can lead to chronic lung disease. Affected individuals may also experience infection or inflammation of the gastrointestinal tract, which can cause diarrhea and weight loss. Abnormal accumulation of immune cells causes enlarged lymph nodes (lymphadenopathy) or an enlarged spleen (splenomegaly) in some people with CVID. Immune cells can accumulate in other organs, forming small lumps called granulomas.

The cause in CVID is unknown in approximately 90 percent of cases. It is likely that this condition is caused by both environmental and genetic factors. While the specific environmental factors are unclear, the genetic influences in CVID are believed to be mutations in genes that are involved in the development and function of immune system cells called B cells. B cells are specialized white blood cells that help protect the body against infection. When B cells mature, they produce special proteins called antibodies (also known as immunoglobulins). These proteins attach to foreign particles, marking them for destruction. Mutations in the genes associated with CVID result in dysfunctional B cells that cannot make sufficient amounts of antibodies.

CVID is estimated to affect 1 in 25,000 to 1 in 50,000 people worldwide, although the prevalence can vary across different populations.

Most cases of CVID are sporadic and occur in people with no apparent history of the disorder in their family. These cases probably result from a complex interaction of environmental and genetic factors.

Published Date: May 01, 2016
Published By: National Institutes of Health