COMT Val158met genotype and striatal D2/3 receptor binding in adults with 22q11 deletion syndrome

Although catechol-O-methyltransferase (COMT) activity evidently affects dopamine function in prefrontal cortex, the contribution is assumed less significant in striatum. We studied whether a functional polymorphism in the COMT gene (Val158Met) influences striatal D2/3R binding ratios (D2/3R BPND) in 15 adults with 22q11 deletion syndrome and hemizygous for this gene, using single photon emission computed tomography and the selective D2/3 radioligand [123I]IBZM. Met hemizygotes had significantly lower mean D2/3R BPND than Val hemizygotes. These preliminary data suggest that low COMT activity may affect dopamine levels in striatum in humans and this may have implications for understanding the contribution of COMT activity to psychiatric disorders