Several genes in the ERK pathway are associated with autism (Stornetta and Zhu, 2011; Fig. 1a, asterisks) and MECP2-duplication mice overexpress several genes in this pathway (Chahrour et al., 2008; notably, Bdnf, Nmdar1, and Ras; Fig. 1a, underlined). Here, BDNF is linked to autism.