The incomplete homozygous SHANK3 deletion (SHANK3−/−) resulted in complete loss of expression of all SHANK3 isoforms in PSC-derived neurons (Supplementary Fig. 19), whereas complete hemizygous SHANK3 deletion (SHANK3+/−), which is the most common genetic abnormality detected in Phelan-McDermid syndrome patients63, resulted in ~50% loss of expression of the longest SHANK3 isoform64. This evidence concerns the gene SHANK3 and Phelan-McDermid syndrome.