1p36 deletion syndrome is a disorder that typically causes intellectual disabilities. Most affected individuals do not speak or speak only a few words. They may have temper tantrums, bite themselves, or exhibit other behavior problems. Most have structural abnormalities of the brain, and seizures occur in more than half of individuals with this disorder. Affected individuals usually have weak muscle tone (hypotonia) and difficulty swallowing (dysphagia).

1p36 deletion syndrome is caused by the deletion of a piece of genetic material from a specific region in the short (p) arm of chromosome 1. In about 50 percent of people with this condition, the deleted region includes the tip of the p arm of chromosome 1. Around 29 percent of affected individuals have deletions that include a section near the end of the chromosome. The remaining 21 percent have complex rearrangements of genetic material that involve this region.

1p36 deletion syndrome is estimated to affect 1 in 5,000 newborns each year in the United States.

Most cases of 1p36 deletion syndrome are not inherited. They are the result of a chromosomal deletion that occurs as a random event during the formation of reproductive cells (eggs or sperm) or in early fetal development. Affected people typically have no history of the disorder in their family.

Published Date: March 15, 2024
Published By: National Institutes of Health