COMT Val(158) met genotype and striatal D(2/3) 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 (Val(158) Met) influences striatal D(2/3) R binding ratios (D(2/3) R BP(ND) ) in 15 adults with 22q11 deletion syndrome and hemizygous for this gene, using single photon emission computed tomography and the selective D(2/3) radioligand [(123) I]IBZM. Met hemizygotes had significantly lower mean D(2/3) R 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.