Molecular basis of selected primary immunodeficiency disorders.

Three primary immunodeficiency conditions are discussed: X-linked agammaglobulinemia, severe combined immunodeficiency, and the X-linked lymphoproliferative syndrome. Each condition is associated with a fascinating history since publication of the original description. To a large extent, the immunologic features of these conditions have been defined. Now, the power of recombinant DNA technology is being employed to dissect the molecular mechanisms central to each disease. This review traces the history of these X-linked conditions. Particular emphasis is focused on the molecular defects thus far exposed. In the end, the knowledge provided by this technology will facilitate genetic counseling, define the nature of the gene defects, provide a logical rationale for therapy, and elucidate the role of the X chromosome in lymphocyte ontogeny.