Many distinct disorders have been discovered, most have a genetic base.
The most common primary immunodeficiency is Hypogammaglobulinaemia in which antibody production is deficient. Boys with XLA become unwell after their mother's antibody protection wears off at around 6 months old. CVID can occur at any age when an individual suddenly stops producing antibodies. The result of antibody deficiency is severe, recurrent and unusual infections with poor response to antibiotic treatment. These infections can cause permanent damage and may become life threatening without correct treatment.