The Immunoglobulin Genes: Genetics, Biological and Clinical Significance

The chromosomal organization of immunoglobulin genes, and the synthesis of various heavy and light chains to molecules with an infinitive variety of antibody specificities, is discussed. These molecules carry antigenic determinants (epitopes) that may be individual (idiotypes), shared (isotypes and isoallotypes) or polymorphic (allotypes).

Since biological effector functions correlate with epitopes, its determination can be relevant to clinical disease. In particular, in cases of an excessive or a decreased production of immunoglobulins or of incomplete proteins, the determination of isotypes and allotypes will supply information on the abnormality.

Allotypes are genetic markers that are useful for family and population studies, for investigation of paternity, blood stains, zygosity of twins and other identification problems. Testing for antibodies to immunoglobulins is indicated when severe transfusion reactions occur that cannot be explained by blood cell incompatibility.

Research on the association of immunoglobulin alleles with immune response, and their interactive effect with HLA in diseases, is gradually developing. The study of the Ig and HLA systems may contribute to the elucidation of the aetiology of immunological disorders and malignancies.