What is (are) 18q deletion syndrome ?
18q deletion syndrome is a chromosomal condition that results when a piece of chromosome 18 is missing. The condition can lead to a wide variety of signs and symptoms among affected individuals.  Most people with 18q deletion syndrome have intellectual disability and delayed development that can range from mild to severe, but some affected individuals have normal intelligence and development. Seizures, hyperactivity, aggression, and autistic behaviors that affect communication and social interaction may also occur. Some people with 18q deletion syndrome have a loss of tissue called white matter in the brain and spinal cord (leukodystrophy), structural abnormalities of the brain, or an abnormally small head size (microcephaly).  Other features that are common in 18q deletion syndrome include short stature, weak muscle tone (hypotonia), narrow auditory canals leading to hearing loss, and limb abnormalities such as foot deformities and thumbs that are positioned unusually close to the wrist. Some affected individuals have mild facial differences such as deep-set eyes, a flat or sunken appearance of the middle of the face (midface hypoplasia), a wide mouth, and prominent ears; these features are often not noticeable except in a detailed medical evaluation. Eye movement disorders and other vision problems, genital abnormalities, heart disease, and skin problems may also occur in this disorder.