22q11.2 microdeletion syndrome, known also under the name of DiGeorge syndrome, is the most frequent deletion in the human chromosome. Its prevalence is estimated at about 1:9,700 newborns, but this is probably an underestimation. In over 90% of cases, the disease is caused by de novo microdeletion in the long arm of chromosome 22, and more rarely by microdeletion of the short arm of this chromosome or by a gene TBX1 point mutation. The consequences of these genotypic disorders are developmental anomalies of the third and fourth pharyngeal arches during the foetal life, which leads to abnormal development of the thymus, parathyroid glands and major cardiac vessels. The characteristic triad of symptoms includes a cardiac defect, hypocalcaemic tetany (hypoparathyroidism) and immunodeficiency. The syndrome may also manifest as facial dysmorphia, palate defects, gastrointestinal abnormalities, urogenital malformations, autoimmune diseases and psychiatric disorders. Standard tests to diagnose this syndrome are molecular studies, such as fluorescence in situ hybridization, array comparative genomic hybridization and a type of polymerase chain reaction: multiplex ligationdependent probe amplification. The therapy of DiGeorge syndrome may include: calcium supplementation, surgical correction of cardiac and palate defects, treatment of immunodeficiency by injections of immunoglobulins, stem cell transplantation or, in rare cases, thymus transplantation. The management of DiGeorge syndrome requires a multidisciplinary approach. Early diagnosis and treatment significantly improve patient’s chances for normal functioning in adult life.