Phelan-McDermid syndrome (PMS) is a rare genetic disorder caused by a deletion of the long arm of chromosome 22q13 or by a pathogenic variant in the SHANK3 gene.

The Phelan-McDermid Syndrome Foundation (PMSF) is the largest patient advocacy group (PAG) for Phelan-McDermid syndrome in the world. The PMSF was established to provide critical information and support to empower families affected by this rare condition. PMSF is the organization that believes in the power of the collective patient voice, and the impact of each family story on our ability to truly improve lives.