22q13 Deletion Syndrome (spoken as twenty two q one three), also known as Phelan-McDermid Syndrome, is a genetic disorder caused by a microdeletion on chromosome 22. The deletion occurs at the terminal end of the chromosome at the location designated q13.3. This microdeletion is rarely uncovered by typical genetic screening, therefore a fluorescence in situ hybridization, or FISH, test is recommended to confirm the diagnosis. Recent work indicates Phelan-McDermid Syndrome may also be caused by errors in a single gene (SHANK3/PROSAP2) in the q13.3 region. Errors on the same gene have been associated with Autism Spectrum Disorder (ASD).
This genetic disorder is characterized by general hypotonia, absent to delayed speech, and global developmental delays. There are approximately 600 reported cases of Phelan-Mcdermid Syndrome worldwide
Individuals with a 22q13 deletion can suffer from a range of symptoms, with mild to very serious physical and behavioral characteristics. Possible symptoms are: