This ~0.8 Mb Xq28 duplication (154.4 – 155.2 Mb, hg19) overlaps with the int22h1/int22h2-mediated Xq28 duplication in a region that only harbors RAB39B and CLIC2 (Figure 2), and has recently been reported in three siblings with cognitive impairment, behavioral problems (ADHD and aggressiveness), short stature, and distinctive facial features including high forehead, hypertelorism, broad nasal bridge, thin upper lip, and cupped ears. The gene discussed is RAB39B; the disease is attention deficit-hyperactivity disorder.