SHANK3 and Down syndrome: In addition, Phelan-McDermid Syndrome (OMIM: 606232) and 22q13 Duplication Syndrome involve a reciprocal microdeletion and microduplication, respectively, of the locus 22q13.3, which encodes the dosage-sensitive gene SH3 and multiple ankyrin repeat domains 3 (SHANK3) (MIM: 606230)36–38.