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

Weaver syndrome

Reviewed May 2013

What is Weaver syndrome?

Weaver syndrome is a disorder characterized by skeletal abnormalities and developmental delay. It is considered an overgrowth syndrome because the bones of affected individuals grow and develop more quickly than usual (advanced bone age) both before and after birth. Adult height is typically normal to tall.

In addition to advanced bone age, people with Weaver syndrome may have other skeletal abnormalities, including foot deformities; permanently bent joints, especially those in the fingers (camptodactyly); and broad thumbs. Characteristic features of the head and face include a large head (macrocephaly); flattened back of the head (occiput); a broad forehead; widely spaced eyes (hypertelorism); large, low-set ears; a long, deep groove in the area between the nose and mouth (philtrum); a dimpled chin; and a small lower jaw (micrognathia).

Individuals with Weaver syndrome have a weak, hoarse cry as newborns and delayed development of motor skills such as sitting, standing, and walking in early childhood. They typically have mild intellectual disability and poor coordination and balance. Some affected individuals have abnormalities in the folds (gyri) of the brain, which can be seen by medical imaging. Increased muscle tone (hypertonia); loose, saggy skin; and a soft out-pouching around the belly-button (umbilical hernia) or lower abdomen (inguinal hernia) may also occur in this disorder. People with Weaver syndrome have an increased risk of developing cancer, but the small number of affected individuals makes the exact risk difficult to determine.

How common is Weaver syndrome?

The prevalence of Weaver syndrome is unknown. About 30 cases have been described in the medical literature.

What genes are related to Weaver syndrome?

Weaver syndrome is usually caused by mutations in the EZH2 gene; rare cases associated with mutations in the NSD1 gene have also been reported. The EZH2 gene provides instructions for making a type of enzyme called a histone methyltransferase. Histone methyltransferases modify proteins called histones, which are structural proteins that attach (bind) to DNA and give chromosomes their shape. By adding a molecule called a methyl group to histones (methylation), histone methyltransferases can turn off (suppress) the activity (expression) of certain genes, which is an essential process in normal development. Specifically, the EZH2 enzyme forms part of a protein group called the polycomb repressive complex-2. By turning off particular genes, this complex is involved in the process that determines the type of cell an immature cell will ultimately become (cell fate determination). Mutations in the EZH2 enzyme may disrupt methylation and impair regulation of certain genes in many of the body's organs and tissues, resulting in the abnormalities characteristic of Weaver syndrome.

The NSD1 gene provides instructions for making a protein whose full range of functions is unknown. Researchers believe that this protein controls the expression of certain genes involved in normal growth and development, and can turn genes on or off as needed. The mutations apparently impair the normal regulation of gene expression. A few individuals with NSD1 gene mutations have been diagnosed with Weaver syndrome. However, some researchers believe that these cases should be classified as unusual presentations of a similar disorder called Sotos syndrome, which is caused by NSD1 gene mutations.

Related Gene(s)

Changes in these genes are associated with Weaver syndrome.

  • EZH2
  • NSD1

How do people inherit Weaver syndrome?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Almost all cases result from new mutations in the gene and occur in people with no history of the disorder in their family. In a small number of cases, an affected person inherits the mutation from one affected parent.

Where can I find information about diagnosis or management of Weaver syndrome?

These resources address the diagnosis or management of Weaver syndrome and may include treatment providers.

  • Genetic Testing Registry: Weaver syndrome (

You might also find information on the diagnosis or management of Weaver 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 Weaver syndrome?

You may find the following resources about Weaver 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 Weaver syndrome?

  • camptodactyly-overgrowth-unusual facies
  • Weaver-Smith syndrome
  • WSS

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 Weaver syndrome?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding Weaver syndrome?

autosomal ; autosomal dominant ; camptodactyly ; cancer ; cell ; developmental delay ; disability ; DNA ; enzyme ; gene ; gene expression ; hernia ; histone ; hypertelorism ; imaging ; inguinal ; inherited ; lower jaw ; macrocephaly ; methyl ; methylation ; methyltransferase ; micrognathia ; molecule ; motor ; muscle tone ; mutation ; philtrum ; prevalence ; protein ; syndrome

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Al-Salem A, Alshammari MJ, Hassan H, Alazami AM, Alkuraya FS. Weaver syndrome and defective cortical development: a rare association. Am J Med Genet A. 2013 Jan;161A(1):225-7. doi: 10.1002/ajmg.a.35660. Epub 2012 Dec 13. (
  • Crea F. Histone code, human growth and cancer. Oncotarget. 2012 Jan;3(1):1-2. (
  • Cross NC. Histone modification defects in developmental disorders and cancer. Oncotarget. 2012 Jan;3(1):3-4. (
  • Douglas J, Hanks S, Temple IK, Davies S, Murray A, Upadhyaya M, Tomkins S, Hughes HE, Cole TR, Rahman N. NSD1 mutations are the major cause of Sotos syndrome and occur in some cases of Weaver syndrome but are rare in other overgrowth phenotypes. Am J Hum Genet. 2003 Jan;72(1):132-43. Epub 2002 Dec 2. (
  • Gibson WT, Hood RL, Zhan SH, Bulman DE, Fejes AP, Moore R, Mungall AJ, Eydoux P, Babul-Hirji R, An J, Marra MA; FORGE Canada Consortium, Chitayat D, Boycott KM, Weaver DD, Jones SJ. Mutations in EZH2 cause Weaver syndrome. Am J Hum Genet. 2012 Jan 13;90(1):110-8. doi: 10.1016/j.ajhg.2011.11.018. Epub 2011 Dec 15. (
  • Neylon OM, Werther GA, Sabin MA. Overgrowth syndromes. Curr Opin Pediatr. 2012 Aug;24(4):505-11. doi: 10.1097/MOP.0b013e3283558995. Review. (
  • Rio M, Clech L, Amiel J, Faivre L, Lyonnet S, Le Merrer M, Odent S, Lacombe D, Edery P, Brauner R, Raoul O, Gosset P, Prieur M, Vekemans M, Munnich A, Colleaux L, Cormier-Daire V. Spectrum of NSD1 mutations in Sotos and Weaver syndromes. J Med Genet. 2003 Jun;40(6):436-40. (
  • Tatton-Brown K, Hanks S, Ruark E, Zachariou A, Duarte Sdel V, Ramsay E, Snape K, Murray A, Perdeaux ER, Seal S, Loveday C, Banka S, Clericuzio C, Flinter F, Magee A, McConnell V, Patton M, Raith W, Rankin J, Splitt M, Strenger V, Taylor C, Wheeler P, Temple KI, Cole T; Childhood Overgrowth Collaboration, Douglas J, Rahman N. Germline mutations in the oncogene EZH2 cause Weaver syndrome and increased human height. Oncotarget. 2011 Dec;2(12):1127-33. (
  • Tatton-Brown K, Rahman N. The NSD1 and EZH2 overgrowth genes, similarities and differences. Am J Med Genet C Semin Med Genet. 2013 May;163C(2):86-91. doi: 10.1002/ajmg.c.31359. Epub 2013 Apr 16. (


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: May 2013
Published: February 8, 2016