Phelan-McDermid syndrome and new treatment medications

Phelan-McDermid syndrome new treatments may improve some patients’ symptoms – more research necessary.

chromosome 17

Phelan-McDermid syndrome (PMS) is a disorder caused by deletions of the distal segment of 22q
(22q13.3). The main factor in this condition is haploinsufficiency of the SHANK3 gene located at this
segment. Mutations of this gene produce the similar phenotype, and patients with these mutations
also may be considered as patients with PMS. The main manifestations of PMS are neonatal hypotonia,
developmental delay, delay in language development, behavioral disturbances, sleep disturbances,
autism spectrum disorder, and sometimes seizures. Growth is normal, dysmorphic features are
generally mild. Intellectual disability becomes more evident with increasing age. A diagnosis of PMS
requires molecular cytogenetic examination (in cases with deletions) or testing of the SHANK3
gene (usually in the process of whole exome sequencing). Differential diagnosis includes non-
syndromal autism spectrum disorder, Prader-Willi syndrome, Angelman syndrome and some other
conditions. Patients with PMS require the care of multidisciplinary teams including
pediatricians, neurologists, psychiatrists, endocrinologists, speech and occupational therapists.
Cardiologists, nephrologists, dentists may be also needed for some patients. There are several
reports of treatment of PMS patients using several medications. Risperidone produced significant
improvement in behavioral problems. Intranasal insulin may improve motor activities and cognitive
functions. Insulin growth factor also may improve social impairments and restrictive behavior.
Larger study populations are required to test the therapeutic effect and safety of all these
methods. Some other promising results may be found in experimental work testing different drugs
in a Shank3 knockout mouse (model of human PMS).

Cammarata Scalisi F. et al. “Clinical and genetic aspects of Phelan-McDermid
syndrome: an interdisciplinary approach to management”. “Genes” (Basel) 2022, v.
13:504.

Chromosome Disorder Outreach Inc. medical geneticist and medical advisor Dr. Iosif Lurie M.D. Ph.D examines newly published research studies to locate the most important and relevant for our members. Synopses of these articles are then posted to our website’s research pages. For more information on any article please contact info@chromodisorder.org