DiGeorge Syndrome (DGS) is a primary immunodeficiency, often but not always, characterized by cellular (T-cell) deficiency, characteristic facies, congenital heart disease and hypocalcemia. DGS is caused by abnormal formation of certain tissues during fetal development. This syndrome is caused by the deletion of a small piece of chromosome 22. As such, it is recommended that the name "22q11.2 deletion syndrome (22q11.2DS)" be used. The syndrome was described in 1968 by the pediatric endocrinologist Angelo DiGeorge.
Diagnosis: The 22q11.2 deletion syndrome is diagnosed in individuals with a submicroscopic deletion of chromosome 22 detected by fluorescence in situ hybridization. Such genetic testing is widely available for the clinical and prenatal testing of the 22q11.2 deletion syndrome. They may have variant deletions of DiGeorge syndrome that may be detectable on a research basis only or with other more advanced clinical testing method.
Epidemology: 22q11.2 deletion syndrome was estimated to affect between one in 2000 and one in 4000 live births. It is one of the most common causes of mental retardation due to a genetic deletion syndrome. The chances of a 22q11.2DS patient having an affected child is 50% for each pregnancy; Parents who have affected children, but who were unaware of their own genetic conditions, are now being diagnosed as genetic testing become available. Recently, the syndrome has been estimated to affect up to one in 2000 live births. Testing for 22q11.2DS in over 9500 pregnancies revealed a prevalence rate of 1/992.