Deletions of human chromosome 22 and associated birth defects.

Investigations into the genetic basis of DiGeorge syndrome have shown that in the majority of cases there are DNA deletions from the long arm of chromosome 22, at 22q11. Similar deletions are now known to be present in a wide range of conditions with overlapping clinical features, and are an important cause of familial congenital heart defect. Deletions within 22q11 have also been identified in individuals with no clinical complications.