SLC9A9 is a Na+/H+ exchanger protein that is localized to the golgi and postgolgi endocytic compartments (Nakamura et al., 2005). Additional studies also support SLC9A9 as an AD/HD candidate. A family-based association study found several SNPs in different regions of SLC9A9 that were nominally associated (most significant result: P=0.01, odds ratio=1.61) with the DSM-IV combined type AD/HD (Brookes et al., 2006). In addition, a genome-wide linkage analysis for AD/HD identified a marker located in SLC9A9, D3S1569, that showed weak linkage (single-point logarithm of the odds: 1.37) with AD/HD (Fisher et al., 2002). Among the candidate genes examined in a recent genome-wide association study, SLC9A9 showed the strongest evidence for association with AD/HD measures (Lasky-Su et al., 2008).
