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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

1p36 deletion syndrome

Reviewed January 2014

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.

Related Chromosome(s)

Changes involving this chromosome are associated with 1p36 deletion syndrome.

  • 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.

  • Gene Review: 1p36 Deletion Syndrome (
  • Genetic Testing Registry: Chromosome 1p36 deletion syndrome (

You might also find information on the diagnosis or management of 1p36 deletion syndrome in Educational resources and Patient support.

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?

  • chromosome 1p36 deletion syndrome
  • distal monosomy 1p36
  • monosomy 1p36 syndrome

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines ( and How are genetic conditions and genes named? ( in the Handbook.

What if I still have specific questions about 1p36 deletion syndrome?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding 1p36 deletion syndrome?

chromosome ; deletion ; disability ; distal ; dysphagia ; gastrointestinal ; genitalia ; hypoplasia ; hypotonia ; inherit ; inherited ; 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.


  • Battaglia A, Hoyme HE, Dallapiccola B, Zackai E, Hudgins L, McDonald-McGinn D, Bahi-Buisson N, Romano C, Williams CA, Brailey LL, Zuberi SM, Carey JC. Further delineation of deletion 1p36 syndrome in 60 patients: a recognizable phenotype and common cause of developmental delay and mental retardation. Pediatrics. 2008 Feb;121(2):404-10. doi: 10.1542/peds.2007-0929. Erratum in: Pediatrics. 2008 May;121(5):1081. Braley, Lisa L [corrected to Brailey, Lisa L]. (
  • Battaglia A. Del 1p36 syndrome: a newly emerging clinical entity. Brain Dev. 2005 Aug;27(5):358-61. Review. (
  • Gajecka M, Mackay KL, Shaffer LG. Monosomy 1p36 deletion syndrome. Am J Med Genet C Semin Med Genet. 2007 Nov 15;145C(4):346-56. Review. (
  • Gene Review: 1p36 Deletion Syndrome (
  • Heilstedt HA, Ballif BC, Howard LA, Lewis RA, Stal S, Kashork CD, Bacino CA, Shapira SK, Shaffer LG. Physical map of 1p36, placement of breakpoints in monosomy 1p36, and clinical characterization of the syndrome. Am J Hum Genet. 2003 May;72(5):1200-12. Epub 2003 Apr 8. (
  • Lahortiga I, Vázquez I, Belloni E, Román JP, Gasparini P, Novo FJ, Zudaire I, Pelicci PG, Hernández JM, Calasanz MJ, Odero MD. FISH analysis of hematological neoplasias with 1p36 rearrangements allows the definition of a cluster of 2.5 Mb included in the minimal region deleted in 1p36 deletion syndrome. Hum Genet. 2005 May;116(6):476-85. Epub 2005 Mar 3. (
  • Lee ML, Tsao LY, Wang BT, Lee MH, Chiu IS. Revisit on a distinctive chromosome 1p36 deletion syndrome: report of one case and review of the English literature. Int J Cardiol. 2004 Sep;96(3):477-80. Review. (
  • Shaffer LG, Heilstedt HA. Terminal deletion of 1p36. Lancet. 2001 Dec;358 Suppl:S9. (


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.

Reviewed: January 2014
Published: February 8, 2016