Immunological aspects of 22q11.2 deletion syndrome

Abstract

Chromosome 22q11 deletion is the most common chromosomal deletion syndrome and is found in the majority of patients with DiGeorge syndrome and velo-cardio-facial syndrome. Patients with CHARGE syndrome may share similar features. Cardiac malformations, speech delay, and immunodeficiency are the most common manifestations. The immunological phenotype may vary widely between patients. Severe T lymphocyte immunodeficiency is rare-thymic transplantation offers a new approach to treatment, as well as insights into thymic physiology and central tolerance. Combined partial immunodeficiency is more common, leading to recurrent sinopulmonary infection in early childhood. Autoimmunity is an increasingly recognized complication. New insights into pathophysiology are reviewed.

Fig. 1

Biopsy from the thigh of a patient with thymic aplasia, following thymic transplantation. Skeletal muscle is shown with thymic tissue at the top right. Cytokeratin (CK) staining identifies thymus tissue (inset a), CD1a and Ki-67 identify cortical thymocytes (inset b, c), and CD3 identifies T lymphocytes (inset d). (Courtesy of Dr. Graham Davies, Great Ormand Street Hospital, London—copyright retained)