In several studies, hiPSC-derived neurons have been examined from individuals with PMS and show a reduction in the number of synapses in SHANK3-deficient neurons, together with smaller cell bodies, more extensively branched neurites, reduced motility, impaired dendritic arborization, and major deficits in excitatory, but not inhibitory, synaptic activity [31–36]. The gene discussed is SHANK3; the disease is premenstrual tension.