LACK OF CORRELATION BETWEEN IMPAIRED T-CELL PRODUCTION, IMMUNODEFICIENCY, AND OTHER PHENOTYPIC FEATURES IN CHROMOSOME 22Q11.2 DELETION SYNDROMES (DIGEORGE-SYNDROME VELOCARDIOFACIAL SYNDROME)

Monosomic deletions of chromosome 22q11.2 are the leading cause of DiG eorge syndrome, velocardiofacial syndrome, and conotruncal anomaly fac e syndrome. DiGeorge syndrome was originally described as an immunodef iciency disorder secondary to impaired T cell production due to thymic aplasia or hypoplasia; however, the frequency of immunodeficiency in the other clinical syndromes associated with the chromosome 22q11.2 mi crodeletion has not been previously investigated. This study examines the frequency and severity of impaired T cell production and immunodef iciency in chromosome 22q11.2 deletion syndromes and the relationship of the immunodeficiency to specific phenotypic features. Sixty patient s over 6 months of age with the characteristic chromosome 22q11.2 dele tion underwent immunologic evaluations. Seventy-seven percent of patie nts with chromosome 22q11.2 deletions were found to have evidence of i mmunocompromise. The severity of the immunodeficiency did not correlat e with any particular phenotypic feature, nor was it restricted to pat ients who were categorized as having DiGeorge syndrome, Therefore, imp aired T cell production and impaired immunologic function are common i n patients with deletions of chromosome 22q11.2, The presence or sever ity of the immunocompromise cannot be predicted based on other phenoty pic features and each child should be individually assessed for immune function. (C) 1998 Academic Press.