Secondary to CD19+ B-cell destruction, patients develop a progressive decrease in all immunoglobulin isotypes (IgG, IgA and IgM): some in a form of dysgammaglobulinemia (deficiency of one or more, but not all, classes of immunoglobulins) and others in the form of agammaglobulinemia (extremely low level of all classes of immunoglobulins). This evidence concerns the gene CD19 and dysgammaglobulinemia.