Phelan-McDermid Syndrome Clinical Trials and Treatments

Phelan-McDermid Syndrome results from deletion of chromosome 22q13 (the smallest deletion is 100 kb involving only SHANK3, while larger deletions involve multiple adjacent genes). The SHANK3 gene encodes a scaffold protein crucial for dendritic spine formation and stabilization, synaptic transmission, and neurodevelopment. SHANK3 is highly expressed in the brain and is critical for proper synaptic function and plasticity.

The most common symptoms of Phelan-McDermid Syndrome include Developmental delay affecting motor, cognitive, and language skills, Autism spectrum disorder features including social communication difficulties, Severe speech and language impairment or absence of speech, Hypotonia and motor coordination problems, Seizures in 25-40% of affected individuals, among others. About 1 in 7,300 people, according to a 2026 Autism Research estimate coauthored by Neuren Pharmaceuticals staff; more than 2,200 people have been diagnosed worldwide, according to MedlinePlus, and many more are thought to be undiagnosed. Symptoms can range from mild to severe and may vary between individuals.

Trial Friend lists all active clinical trials for Phelan-McDermid Syndrome from ClinicalTrials.gov, with eligibility criteria translated into plain English. Patients can filter by trial phase and recruitment status, search by location, and use the Match Me tool to score trials against their profile. Research in Phelan-McDermid syndrome includes gene therapy aimed at the SHANK3 defect and drugs that act on brain signaling. On November 3, 2026, ClinicalTrials.gov listed JAG201, a one-time gene therapy given into the fluid spaces of the brain, as recruiting children aged 2 to 9 (NCT06662188, Jaguar Gene Therapy), a similar RB001 study in China as active (NCT07014020), and 2 Phase 3 studies of NNZ-2591, a medicine taken by mouth twice a day, recruiting children aged 3 to 12 (NCT07281079 and NCT07593391, Neuren Pharmaceuticals).

As of October 21, 2026, no current FDA drug label names Phelan-McDermid Syndrome as a condition the drug treats.

Phelan-McDermid Syndrome is caused by variants in the SHANK3 gene. Most cases are a de novo 22q13.3 deletion including SHANK3, detected by chromosomal microarray; a minority are SHANK3 sequence variants or ring chromosome 22.

It follows autosomal dominant, usually de novo inheritance. About 1 in 7,300 people, according to a 2026 Autism Research estimate coauthored by Neuren Pharmaceuticals staff; more than 2,200 people have been diagnosed worldwide, according to MedlinePlus, and many more are thought to be undiagnosed. Genetic testing confirms the diagnosis.

Yes. Genetic testing for Phelan-McDermid Syndrome looks at the SHANK3 gene. Most cases are a de novo 22q13.3 deletion including SHANK3, detected by chromosomal microarray; a minority are SHANK3 sequence variants or ring chromosome 22.

It follows autosomal dominant, usually de novo inheritance.

A confirmed variant establishes the diagnosis and is often required to enroll in gene-specific trials. The labs currently offering the test are listed in the Genetic Testing section of this page, pulled live from the NIH Genetic Testing Registry. A genetic counselor can help interpret the result and decide which relatives should be tested.

Eligibility for Phelan-McDermid Syndrome clinical trials depends on factors like age, diagnosis, treatment history, and overall health. Each trial sets its own inclusion and exclusion criteria. Trial Friend translates these requirements from medical language into plain English so patients can review them more easily. The Match Me tool can score your profile against active trials to help identify studies that may be a fit.

Participating in a Phelan-McDermid Syndrome clinical trial typically involves scheduled visits, medical tests, and close monitoring by a research team. Depending on the study phase, you may receive an investigational treatment, a placebo, or the current standard of care. Trials may last from a few weeks to several years. Study participation is voluntary, and you can withdraw at any time.