We found significant associations with SLC9A9 and AD/HD measures in our families. Our data suggest that disruption of this gene contributes to aspects of the AD/HD-like phenotype found in the inversion family. Our association finding of SLC9A9 with AD/HD is of particular interest as this gene has been identified as an AD/HD candidate in several studies. These include association findings in our own population and another independent population (Brookes et al., 2006; Lasky-Su et al., 2008), suggestive evidence for linkage in one study (Fisher et al., 2002), and an inversion that directly disrupts SLC9A9 cosegregates with an AD/HD-like phenotype in a family (De Silva et al., 2003; Efron et al., 2003). Our findings, combined with the findings of earlier studies, warrant further investigation of SLC9A9 in relation to AD/HD and other behavioral disorders.
