22q11.2 deletion syndrome (22q11DS) is a genetic syndrome associated with a microdeletion of the chromosome 22 band q11.2 with an estimated prevalence between 1:2,500 and 1:4,000. Studies of school-age children have shown that individuals with 22q11DS have high rates of psychiatric morbidity. In particular, by late adolescence, about 30% of patients with 22q11DS develop psychotic symptoms. One of the genes located in the microdeletion region of 22q11DS is the catechol-O-methyl transferase (COMT) which codes for an enzyme critically involved in the catabolic clearance of dopamine. COMT is critically involved in cognitive related disturbances, and it has often been suggested as a sensitive factor in the development of psychiatric disorders. Several studies have been conducted on the impact of COMT functional polymorphism in 22q11DS and its related cognitive/psychiatric correlates. In this review, we summarize mainly current knowledge on the correlation between schizophrenia/cognitive related symptoms and COMT genetic variations in 22q11DS. A selective literature review on this topic was undertaken. COMT might play an important role in modulating cognitive functions in 22q11DS but a clear relationship between COMT polimorphism and schizophrenia in 22q11DS need further investigation. Despite controversial results, 22q11DS represent a powerful model for studying the role of COMT and other genetic variations in schizophrenia. This is due to high risk in 22qDS patients of developing this disorder and their relative genetic homogeneity. Further research is needed to evaluate all of the polymorphic markers in the COMT gene and its nearby regulatory elements for association with schizophrenia. Identification of specific COMTdependent molecular, cellular and circuit deficits will provide targets for the development of more efficient treatments for the cognitive and psychiatric symptoms in 22q11DS.
Keywords: 22q11.2 deletion syndrome, COMT, schizophrenia, Catechol O Methyl Transferase, Deletion Syndrome, ADHD, OCD, prefrontal cortex, Obsessive compulsive disorder