Although the severity of the condition and the associated features vary from person to person, common signs and symptoms include poor muscle tone in newborns; developmental delay; mild to severe intellectual disability; delayed or absent speech; behavioral abnormalities; and seizures. Most cases of isodicentric chromosome 15 syndrome occur sporadically in people with no family history of the condition. Treatment is based on the...

Common features shared by many people with this duplication include developmental delay, intellectual disability, hypotonia (low muscle tone), seizures, high and/or cleft palate (roof of the mouth), scoliosis, slow growth, communication difficulties, behavioral problems, and distinctive facial features.