COMT and 22q11.2 deletion syndrome: In velo-cardio-facial syndrome (VCFS), a rare disorder with an increased risk of schizophrenia resulting from a microdeletion in 22q11.2, patients are known to lack one copy of COMT. In this patient group available evidence suggests that genotype effects of COMT Val158Met on cognitive performance are critically dependent on the maturational stage of the brain (Gothelf et al. 2005).