The SHANK3 gene provides instructions for making a protein that is found in many of the body's tissues but is most abundant in the brain. The SHANK3 protein plays a role in the functioning of synapses, which are the connections between nerve cells (neurons) where cell-to-cell communication occurs. Within synapses, the SHANK3 protein acts as a scaffold that supports the connections between neurons, ensuring that the signals sent by one neuron are received by another.~The SHANK3 protein is also involved in the formation and maturation of dendritic spines. Dendrites are specialized extensions from neurons that are essential for the transmission of nerve impulses. Dendritic spines are small outgrowths from dendrites that further help transmit nerve impulses and increase communication between neurons.