Methods and assays are disclosed for treating subjects with 22q13 deletion syndrome or SHANK3 deletion or duplication, mutation or reduced expression, where the methods comprise administering to the subject insulin-like growth factor 1 (IGF-1), IGF-1-derived peptide or analog, growth hormone, an AMPAkine, a compound that directly or indirectly enhances glutamate neurotransmission, including by inhibiting inhibitory (most typically GABA) transmission, or an agent that activates the growth hormone receptor or the insulin-like growth factor 1 (IGF-1) receptor, or a downstream signaling pathway thereof.
