Diagnosis is difficult because of the diversity of phenotypes seen in people with CVID. For example, serum immunoglobulin levels in people with CVID vary greatly. Generally, people can be grouped as follows: no immunoglobulin production, immunoglobulin (Ig) M production only, or both normal IgM and IgG production. Additionally, B cell numbers are also highly variable. 12% of people have no detectable B cells, 12% have reduced B cells, and 54% are within the normal range. In general, people with CVID display higher frequencies of naive B cells and lower frequencies of class-switched memory B cells. Frequencies of other B cell populations, such as IgD memory B cells, transitional B cells, and CD21 B cells, are also affected, and are associated with specific disease features. Although CVID is often thought of as a serum immunoglobulin and B cell-mediated disease, T cells can display abnormal behavior. Affected individuals typically present with low frequencies of CD4+, a T-cell marker, and decreased circulation of regulatory T cells and iNKT cell. Notably, approximately 10% of people display CD4+ T cell counts lower than 200 cells/mm3; this particular phenotype of CVID has been named LOCID (Late Onset Combined Immunodeficiency), and has a poorer prognosis than classical CVID. Types
The following types of CVID have been identified, and correspond to mutations in different gene segments. Treatment
Treatment options are limited, and usually include lifelong immunoglobulin replacement therapy. This therapy is thought to help reduce bacterial infections.
Signs of a gastrovascular infection include abdominal pain, nausea, bloating, vomiting, diarrhea, and weight loss. Many individuals with CVID have an impaired ability to absorb nutrients, including vitamins, proteins, minerals, fats, and sugar within the digestive tract.Due to changes in development in B cells, some individuals with CVID have accumulations of lymphocytes in lymphoid tissues. This can cause mild to severely swollen lymph nodes or inflammation of the spleen. In addition, a certain percentage of individuals with CVID are more susceptible to developing certain forms of cancer, more so than those without the condition. The two most common cancers in common variable immunodeficiency patients include lymphoma and certain stomach cancers. The risk for these given cancers is almost fifty times greater in common variable immunodeficiency patients than those without. People with common variable immunodeficiency have trouble fighting off infections due to the lack of antibodies produced which normally resist invading microbes. Due to impaired antibody development vaccines are not effective. Recurring bacterial infections are generally found in the upper and lower areas of the respiratory tract. Many who have a recurring lung infection, report developing, chronic lung diseases, and potentially life-threatening complications later in life. Causes
The cause of CVID is poorly understood. A likely cause are Deletions in genes that encode cell surface proteins and cytokine receptors, such as CD19, CD20, CD21, and CD80. Additionally, the disease is defined by T cell defects, namely reduced proliferative capacity. The condition is hard to diagnose, taking on average 6–7 years after onset. CVID is a primary immunodeficiency.