What is Phelan-McDermid syndrome?
Phelan-McDermid syndrome is a rare chromosomal condition where individuals are missing a portion of their 22nd chromosome. People Phean-McDermid may have low muscle tone, normal to fast growth, absent or severely delayed speech, intellectual disability, and some characteristic facial features. Some individuals may fall on the autism spectrum. Not everyone with Phelan-McDermid syndrome is affected in the the same way. Contact the Phelan-McDermid Syndrome Foundation to learn more about this condition.