ATRX and Cognitive impairment: Similarly, ATR-X model mice lacking Atrx exon 2 (Nogami et al., 2011) show phenotypes similar to the symptoms of ID noted in humans, cognitive deficits (Kaufmann and Moser, 2000; Levenga and Willemsen, 2012), and abnormal dendritic formation (Shioda et al., 2011).