Synaptic Arc also associates with the synaptic scaffolding protein PSD-95/Dlg4, which complexes with the tyrosine kinase FYN [457,458,459], allowing it to regulate brain-derived neurotrophic factor (BDNF) signalling through tyrosine receptor kinase B (TrkB), a major pathway for synapse maturation, plasticity and neurodevelopmental disorders [460]. This evidence concerns the gene FYN and neurodevelopmental disorder.