Question: What is (are) 22q11.2 deletion syndrome ?
Answer: 22q11.2 deletion syndrome is a spectrum disorder that includes conditions formerly called DiGeorge syndrome; velocardiofacial syndrome; conotruncal anomaly face syndrome; cases of Opitz G/BBB syndrome; and Cayler cardiofacial syndrome. The features and severity can vary greatly among affected people. Signs and symptoms may include cleft palate, heart defects, recurrent infections, unique facial characteristics, feeding problems, immune system disorders, kidney abnormalities, hypoparathyroidism, thrombocytopenia, scoliosis, hearing loss, developmental delay, and learning disabilities. People with this condition are also more likely to develop certain autoimmune disorders and personality disorders. In most cases, the syndrome occurs for the first time in the affected person; about 10% of cases are inherited from a parent. It is inherited in an autosomal dominant manner.
Source: GARD

Question: What causes 22q11.2 deletion syndrome ?
Answer: What causes 22q11.2 deletion syndrome? 22q11.2 deletion syndrome is caused by a missing piece (deletion) of part of chromosome 22 in each cell. The deletion occurs near the middle of the chromosome at a location designated q11.2. Most people with 22q11.2 deletion syndrome are missing a piece of the chromosome that contains about 30 to 40 genes, many of which have not been well characterized. Some affected people have smaller deletions. Researchers are working to learn more about all of the genes that contribute to the features of 22q11.2 deletion syndrome. The deletion of a particular gene, TBX1, is probably responsible for many of the syndrome's characteristic signs (such as heart defects, a cleft palate, distinctive facial features, hearing loss, and low calcium levels). Loss of this gene may also contribute to behavioral problems. The loss of another gene, COMT, may also cause increased risk of behavioral problems and mental illness in affected people. The other genes that are deleted likely contribute to the various features of 22q11.2 deletion syndrome.
Source: GARD