Description

A variety of syndrome complexes are now known to be associated with microdeletions of chromosome 22q11, encompassing a very large spectrum of congenital abnormalities. Although it is one of the commonest chromosomal abnormalities, classical Di George syndrome with severe T cell abnormalities is rare. There is, however, a wide spectrum of immunological abnormalities, with variable T cell defects and an increased incidence of immunoglobulin and antibody deficiency, and in some infants a spontaneous increase in T cell numbers may occur in the first few years of life. Immunological abnormalities do not correlate well with other phenotypic features. Definitive diagnosis of the syndrome depends on confirmation of the microdeletion, but clinically indistinguishable syndromes also occur, occasionally associated with a microdeletion of chromosome 10p, but more frequently without any detectable cytogenetic abnormality. Management strategies depend on the degree of the immune defect in the context of other congenital abnormalities. For severe T cell deficiency possible treatments include thymic, bone marrow, or peripheral blood stem cell transplantation, while children with milder T cell or humoral defects are managed supportively with appropriate prophylaxis. Other than in the rare infants with very severe T cell defects the long term outlook rarely depends on the immune defect, usually being linked much more closely with the extent of other abnormalities.