The decrease of the ratio between perforated and non-perforated synapses, also part of the structural phenotype of KIBRA mutants discovered in our study, supports such a view of developmental delay as the prevalence of perforated synapses generally increases during development (Sorra et al., 1998) and with sensory experience (Greenough et al., 1978). Here, WWC1 is linked to Global developmental delay.