<prompt> Answer this question truthfullyWhat does variable immunodeficiency mean?  <response>: <reason> The cause of common variable immunodeficiency has not been identified. Genetic mutations may be recognized as the cause of CVID in about 10 of patients, and familial inheritance accounts for 10-25 of the affected population. Rather than arising from a single genetic mutation, CVID is due to numerous mutations that all are associated with dysfunction in antibody regulation and production. 