Other tests determine how well a person is producing antibodies against specific germs following immunization with a common vaccine, such as a tetanus shot. IgA deficiency is caused by faulty white blood cells called B cells or B lymphocytes. While patients have normal numbers of B cells, these cells do not mature into normal IgA-producing cells. Scientists do not yet know the exact cause or causes for these immature B cells. Sometimes clusters of cases occur in families, and IgA-deficient patients are more likely than the general population to be related to someone with combined variable immunodeficiency, another form of immunodeficiency discussed below.
Research is underway to determine the location of the suspected genes on the involved chromosomes.
There is no specific treatment for selective IgA deficiency. CVI is relatively common. Infants sometimes have symptoms of CVI, though in most cases symptoms do not show up until the second or third decade of life. Most patients with CVI get frequent bacterial infections of the ears, sinuses, bronchi, and lungs. Patients may develop painful swollen joints in the knee, ankle, elbow, or wrist.