Furthermore, alterations in mRNA levels of Cnr1, CDC42 and neuritin have been linked to the development of schizophrenia (Eggan et al., 2008; Hill et al., 2006; Chandler et al., 2010), and alterations in the level of Sorl1 mRNA have been linked to the development of Alzheimer’s disease (Kölsch et al., 2009). Here, NRN1 is linked to early-onset autosomal dominant Alzheimer disease.