GRM5 and fragile X syndrome: Interestingly, dysregulation of mGluR5 has been reported in several profound neurological disorders, such as schizophrenia (Conn et al., 2009; Nickols and Conn, 2014), autistic spectrum disorders (Williams, 2012) and fragile X syndrome (Michalon et al., 2012), altogether pointing towards a pivotal regulatory function for this receptor.