We found an association between COMT haplotypes and CIP. Numerous previous studies of psychiatric disorders and related phenotypes have demonstrated associations with this gene, most commonly with the nonsynonymous Val108/158Met variant (rs4680). This common functional variant was reported to associate with neurocognitive phenotypes hypothesized to be regulated by dopamine in the prefrontal lobe during working memory in schizophrenic patients and controls (Egan et al., 2001; Meyer-Lindenberg et al., 2005).
