PKP4 and neurodevelopmental disorder: We note that 21% of the proteins we discovered in developing synapses either may be regulated by FMRP (Fragile X Mental Retardation Protein)50 (Ptpn11, Lrrc7, Lphn1, Lphn3, Grin1, Grin2b, Dab2ip, Ntrk2, Odz4, Grm5, Pkp4) or are directly implicated by gene mutations in neurodevelopmental disorders, including Erbb2ip51,52, Cnksr2 (refs. 53,54), and Wrp (also known as Srgap3)55.