The 22q11.2 deletion syndrome is caused by a hemizygous microdeletion in the 22q11.2 chromosome region and has an incidence of 1 in 2000–4000 live births.3, 4 Although atypical microdeletions have been described, most of the deletions (around 90%) are 3 Mb in size, which includes approximately 60 genes. The remaining microdeletions (~10%) are 1.5 Mb in size and include approximately 35 genes. Most the genes within the microdeletions are expressed in the brain.4, 5 Patients with the microdeletion exhibit a spectrum of cognitive deficits, and approximately 30% of them develop typical schizophrenia in adolescence or early adulthood.6, 7 It is suggested that the 1.5 Mb microdeletion is sufficient for psychiatric phenotypes, possibly because this deletion encompasses multiple genes involved in the development, maturation and function of neurons and neuronal circuits.4, 8
