Phelan-McDermid Syndrome (PMS) is caused by deletions of the distal long arm of 22 (22q13) or pathogenic mutations of the SHANK3 gene, which plays an important role in the way synapses facilitate efficient neuron-neuron communications in the brain, impacting learning and memory.

First diagnosed in 1985 and further described in 1988 by Dr. Katy Phelan(shown left) et al. as a denovo deletion in 22q13.3, the true prevalence of PMS has not been determined. More than 1400 people have been identified worldwide according the Phelan-McDermid Syndrome Foundation(PMSF).

However, it is believed to be underdiagnosed due to past limitations of genetic testing and lack of specific clinical features. It is known to occur with equal frequency in males and females.

Studies using chromosomal microarray for diagnosis indicate that at least 0.5% of cases of ASD can be explained by mutations or deletions in the SHANK3 gene.  In addition, when ASD is associated with ID, SHANK3 mutations or deletions have been found in up to 2% of individuals.  The rate of SHANK3 insufficiency in ID and ASD is still being determined; however, these findings imply that it is one of the most common single gene causes.

PMSF and the research community are working to try to find treatments and, eventually, cures for PMSF.  At the present, there is no cure for PMS nor are there medications approved specifically for the treatment of PMS.  There are medications to manage the symptoms and comorbid conditions often associated with PMS.

Therefore, understanding the brains of people with this genetic form of autism may provide important insights into the causes of Phelan-McDermid Syndrome and autism spectrum disorder more generally.

By focusing on individuals with specific genetic mutations, a better understanding of how genes and the environment interact is possible.

We would like to thank everyone in the PMS community for considering participation in this groundbreaking research.

We urge families affected by Phelan-McDermid Syndrome to consider registering to participate in Autism BrainNet. You may click here to register for Autism BrainNet. You can call Autism BrainNet personnel at (877) 333-0999 or email them at info(at)