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1p36 deletion syndrome


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).

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 often have unusually short fingers and toes (brachydactyly), permanently bent fingers and toes (camptodactyly), and short feet. They may also have vision or hearing problems. Some affected individuals have abnormalities of the skeleton, heart, gastrointestinal system, kidneys, or genitalia. 

Life expectancy varies in people with 1p36 deletion syndrome, but affected individuals can survive into early adulthood.


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


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.

The size of the deletion varies among affected individuals. The signs and symptoms of 1p36 deletion syndrome are likely caused by the loss of multiple genes that are involved in the development of systems such as the brain, heart, and skeleton.


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.

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. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes usually do not cause any health problems. However, translocations 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 p arm of chromosome 1, which results in the health problems that are characteristic of this disorder.

Other Names for This Condition

  • Chromosome 1p36 deletion syndrome
  • Distal monosomy 1p36
  • Monosomy 1p36 syndrome

Additional Information & Resources

Genetic and Rare Diseases Information Center

Patient Support and Advocacy Resources

Clinical Trials

Catalog of Genes and Diseases from OMIM

Scientific Articles on PubMed


  • 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]. Citation on PubMed
  • Battaglia A. Del 1p36 syndrome: a newly emerging clinical entity. Brain Dev. 2005 Aug;27(5):358-61. doi: 10.1016/j.braindev.2004.03.011. Citation on PubMed
  • 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. doi: 10.1002/ajmg.c.30154. Citation on PubMed
  • 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. doi: 10.1086/375179. Epub 2003 Apr 8. Citation on PubMed or Free article on PubMed Central
  • Jacquin C, Landais E, Poirsier C, Afenjar A, Akhavi A, Bednarek N, Benech C, Bonnard A, Bosquet D, Burglen L, Callier P, Chantot-Bastaraud S, Coubes C, Coutton C, Delobel B, Descharmes M, Dupont JM, Gatinois V, Gruchy N, Guterman S, Heddar A, Herissant L, Heron D, Isidor B, Jaeger P, Jouret G, Keren B, Kuentz P, Le Caignec C, Levy J, Lopez N, Manssens Z, Martin-Coignard D, Marey I, Mignot C, Missirian C, Pebrel-Richard C, Pinson L, Puechberty J, Redon S, Sanlaville D, Spodenkiewicz M, Tabet AC, Verloes A, Vieville G, Yardin C, Vialard F, Doco-Fenzy M. 1p36 deletion syndrome: Review and mapping with further characterization of the phenotype, a new cohort of 86 patients. Am J Med Genet A. 2023 Feb;191(2):445-458. doi: 10.1002/ajmg.a.63041. Epub 2022 Nov 11. Citation on PubMed
  • Lahortiga I, Vazquez I, Belloni E, Roman JP, Gasparini P, Novo FJ, Zudaire I, Pelicci PG, Hernandez 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. doi: 10.1007/s00439-005-1268-1. Epub 2005 Mar 3. Citation on PubMed
  • 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. doi: 10.1016/j.ijcard.2003.04.072. No abstract available. Citation on PubMed
  • Shaffer LG, Heilstedt HA. Terminal deletion of 1p36. Lancet. 2001 Dec;358 Suppl:S9. doi: 10.1016/S0140-6736(01)07022-2. No abstract available. Citation on PubMed

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