 Phelan-McDermid syndrome (PMS) is a neurodevelopmental disorder characterized by psychiatric and neurological features. Most reported cases are caused by 22q13.3 deletions, leading to SHANK3 haploinsufficiency, but also usually encompassing many other genes. While the number of point mutations identified in SHANK3 has increased in recent years due to large-scale sequencing studies, systematic studies describing the phenotype of individuals harboring such mutations are lacking.