Five out of six CMA studies (CytoScan HD, Affymetrix, Santa Clara, CA or custom 22q13.31 array, OGT, Cambridge, UK) were informative of SHANK3 loss, leading to a Phelan-McDermid syndrome-related presentation; in one instance, the CMA was negative due to low-level mosaicism for the ring (8% of metaphases examined). The gene discussed is SHANK3; the disease is Phelan-McDermid syndrome.