FMR1 and fragile X syndrome: The fly has a single homologue of FMR1, and its loss of function causes many phenotypes similar to those associated with FXS patients (Zhang et al, 2001; Morales et al, 2002; Pan et al, 2004; Reeve et al, 2005; Bassell & Warren, 2008; McBride et al, 2012).