The Safety Sleeper

Phelan-McDermid Syndrome

Phelan-McDermid Syndrome

What It Is

Phelan-McDermid syndrome (PMS) can be caused by a few things: by the deletion of a part of chromosome 22 or by a genetic variant; it is a rare genetic condition.

Symptoms of Phelan-McDermid Syndrome

Based on varying genetic descriptions and symptoms, families may come across several explanations of this syndrome, as is the case with many rare conditions. Symptoms of PMS can show up as early as at birth or within the first six months of a child’s life.

With PMS, there can be developmental and intellectual issues, including problems with sleep and eating. The PMS Foundation (PMSF) has over 2,800 disclosed PMS diagnoses, although there are many undiagnosed cases, and about 75% of people with PMS have also received Autism Spectrum Disorder diagnoses. PMS patients don’t sweat as much as others, so overheating is possible.

How Rare It Is

PMS is a rare disease that is found in about 1% of those with autism (which is reported to be between 1/8,000 and 1/15,000). Not every PMS patient will have autism, so these numbers may not be accurate.


The treatment for PMS follows patients’ symptoms, as there are currently not any medications or other treatments for PMS. 

More Resources

For more information, visit these resources: the National Institute of Health’s (NIH) Genetic and Rare Disease Information Center (click here); the National Organization for Rare Disorders: Phelan-McDermid Syndrome (click here); and the National Organization for Rare Disorders: Ring 22 (click here).

Getting Diagnosed

Since PMS is a genetic disorder, receiving a diagnosis will require testing. Here is information on getting diagnosed and tested.

For more information about Phelan-McDermid syndrome, go to

Learn more about how we can help

We are here to help you choose the best bed for your loved one.