Common variable immunodeficiency (CVID) is an immune system disorder that causes you to have low levels of the proteins that help fight infections. If you have CVID, you'll likely have repeated infections in your ears, sinuses and respiratory system. You'll also have an increased risk of digestive disorders, autoimmune disorders, blood disorders and cancer. CVID can be inherited, or you can develop it during your lifetime.
The severity of symptoms can vary greatly between people with CVID. Symptoms of common variable immunodeficiency may appear during childhood or adolescence, though many people don't experience them until adulthood.
If you have CVID, you'll likely experience repeated infections before being diagnosed. The most common types of infections include pneumonia, sinusitis, ear infections and gastrointestinal infections.
In the vast majority of CVID cases, the cause is unknown. In around 10% of people with CVID, a genetic mutation has been identified. Researchers believe that the condition is caused by a combination of both environmental and genetic factors. As of now, the environmental factors are unclear.