Development of hypogammaglobulinaemia in a patient with common variable immunodeficiency.

A 3-year-old boy who developed common variable immunodeficiency was investigated for the development of hypogammaglobulinaemia. During a period of 4 years, the combined deficiency of IgA, IgG2 and IgG4 proceeded to include IgG1 and finally IgG3 and IgM. This order of isotypes of IgG subclass deficiencies corresponded to the gene order for the heavy chain constant region for immunoglobulins on chromosome 14.