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Disease Profile

Hemifacial myohyperplasia

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

<1 / 1 000 000

US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Hypertrophy and asymmetry of the facial muscles


Mouth Diseases; Musculoskeletal Diseases


Hemifacial myohyperplasia (HMH) is a developmental disorder that frequently affects the right side of the face and is commonly seen in males. On the affected side of the face, there are usually enlarged tissues that lead to an abnormal jaw shape.[1] Other features associated with HMH include enlargement of the brain, epilepsy, strabismus, genitourinary system disorders, intellectual disability, and dilation of the pupil on the affected side .[1][2] Asymmetry of the face is more noticeable with age and remains until the end of adolescence when the asymmetry stabilizes.[1][3] The cause of HMH is unknown; but theories suggest an imbalance in the endocrine system, neuronal abnormalitieschromosomal abnormalities, random events in twinning and fetal development, and vascular or lymphatic abnormalities.[2]

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Hemifacial myohyperplasia. Click on the link to view a sample search on this topic.


  1. Pereira-Perdomo DF, Vélez-Forero J, Prada-Madrid R. Hemifacial myohyperplasia sequence. Am J Med Genet A. July 2010; https://www.ncbi.nlm.nih.gov/pubmed/20583183. Accessed 7/13/2011.
  2. Lee S, Sze R, Murakami C, Gruss J, Cunningham M. Hemifacial myohyperplasia: description of a new syndrome. Am J Med Genet. November 2001; https://www.ncbi.nlm.nih.gov/pubmed/11746014. Accessed 7/13/2011.
  3. Miranda RT, Barros LM, Santos LA, Bonan PR, Martelli H Jr. Clinical and imaging features in a patient with hemifacial hyperplasia. J Oral Sci. 2010; https://www.jstage.jst.go.jp/article/josnusd/52/3/509/_pdf. Accessed 7/13/2011.