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1p36 deletion syndrome
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Reviewed March 2009
What is 1p36 deletion syndrome?
1p36 deletion syndrome is a disorder that typically causes severe intellectual disability. 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 swallowing difficulties (dysphagia).
People with 1p36 deletion syndrome have a small head that is also unusually short and wide in proportion to its size (microbrachycephaly). Affected individuals also have distinctive facial features including deep-set eyes with straight eyebrows; a sunken appearance of the middle of the face (midface hypoplasia); a broad, flat nose; a long area between the nose and mouth (philtrum); a pointed chin; and ears that are low-set, rotated backwards, and abnormally shaped.
People with 1p36 deletion syndrome may have vision or hearing problems. Some have abnormalities of the skeleton, heart, gastrointestinal system, kidneys, or genitalia.
How common is 1p36 deletion syndrome?
1p36 deletion syndrome is believed to affect between 1 in 5,000 and 1 in 10,000 newborns. However, this may be an underestimate because some affected individuals are likely never diagnosed.
What are the genetic changes related to 1p36 deletion syndrome?
1p36 deletion syndrome is caused by a deletion of genetic material from a specific region in the short (p) arm of chromosome 1. The signs and symptoms of 1p36 deletion syndrome are probably related to the loss of multiple genes in this region. The size of the deletion varies among affected individuals.
Read more about chromosome 1.
Can 1p36 deletion syndrome be inherited?
Most cases of 1p36 deletion syndrome are not inherited. They result from 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.
About 20 percent of people with 1p36 deletion syndrome inherit the chromosome with a deleted segment from an unaffected parent. In these cases, the parent carries a chromosomal rearrangement called a balanced translocation, in which no genetic material is gained or lost. Balanced translocations usually do not cause any health problems; however, they can become unbalanced as they are passed to the next generation. Children who inherit an unbalanced translocation can have a chromosomal rearrangement with extra or missing genetic material. Individuals with 1p36 deletion syndrome who inherit an unbalanced translocation are missing genetic material from the short arm of chromosome 1, which results in birth defects and other health problems characteristic of this disorder.
Where can I find information about diagnosis or management of 1p36 deletion syndrome?
These resources address the diagnosis or management of 1p36 deletion syndrome and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about 1p36 deletion syndrome?
You may find the following resources about 1p36 deletion syndrome helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for 1p36 deletion syndrome?
What if I still have specific questions about 1p36 deletion syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding 1p36 deletion syndrome?
chromosome ; deletion ; distal ; dysphagia ; gastrointestinal ; genitalia ; hypoplasia ; hypotonia ; monosomy ; muscle tone ; philtrum ; rearrangement ; reproductive cells ; sperm ; syndrome ; translocation
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (8 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.