X-linked immunodeficiencies.

Abstract

Advances in the molecular biology of diseases of the immune system are rapidly unfolding in many areas Immunologists have become aware that many of the rare congenital immunodeficiency patients they encounter have specific genetic defects, many of them X-linked. Two X-linked genes, those for properdin and cytochrome b-245 beta chain, have been cloned and proven to cause, respectively, a complement system disorder, properdin deficiency, and the phagocyte-killing defect chronic granulomatous disease. There are at least five other genetic loci responsible for X-linked diseases involving lymphocytes. These appear to be disorders of distinct gene products which may be required for development, survival, or function of particular lymphocyte lineages. None of these genes have been cloned, and there are no biochemical or immunological indicators as to the primary pathogenesis. Linkage analysis has been used to establish a regional localization for each gene defect. Further genetic clues, such as affected individuals with chromosomal translocations or deletions, have not been detected except in chronic granulomatous disease and, recently, X-linked lymphoproliferative syndrome.