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Disease Profile

Hypereosinophilic syndrome

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.

1-9 / 100 000

US Estimated

Europe Estimated

Age of onset

All ages





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)

HES; Hypereosinophilic syndrome, idiopathic


Blood Diseases; Heart Diseases


Hypereosinophilic syndrome (HES) refers to a rare group of conditions that are associated with persistent eosinophilia with evidence of organ involvement. Signs and symptoms vary significantly based on which parts of the body are affected. Although any organ system can be involved in HES, the heart, central nervous system, skin, and respiratory tract are the most commonly affected. The condition was originally thought to be "idiopathic" or of unknown cause. However, recent advances in diagnostic testing have allowed a cause to be identified in approximately a quarter of cases. Management varies based on the severity of the condition and whether or not an underlying cause has been identified but generally includes imatinib or corticosteroids as an initial treatment.[1][2][3]


The signs and symptoms of hypereosinophilic syndrome can vary significantly depending on which part(s) of the body are affected. Frequent symptoms listed by body system include:[1][2][3]

  • Skin rashes, itching, and edema.
  • Lung asthma, cough, difficulty breathing, recurrent upper respiratory infections, and pleural effusion.
  • Gastrointestinal abdominal pain, vomiting, and diarrhea.
  • Musculoskeletal arthritis, muscle inflammation, muscle aches, and joint pain.
  • Nervous system vertigo, paresthesia, speech impairment, and visual disturbances.
  • Heart congestive heart failure, cardiomyopathy, pericardial effusion, and myocarditis.
  • Blood deep venous thrombosis, and anemia.

Affected people can also experience a variety of non-specific symptoms such as fever, weight loss, night sweats and fatigue.[1][2]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
30%-79% of people have these symptoms
Pulmonary infiltrates
Lung infiltrates
5%-29% of people have these symptoms
Low platelet count
Percent of people who have these symptoms is not available through HPO
Abnormality of the nervous system
Neurologic abnormalities
Neurological abnormality

[ more ]

Low number of red blood cells or hemoglobin
Autosomal dominant inheritance
Endocardial fibrosis
High blood eosinophil count
Enlarged liver
Muscle ache
Muscle pain

[ more ]

Myeloproliferative disorder
Myocardial eosinophilic infiltration
Itchy skin
Skin itching

[ more ]

Recurrent bronchitis
Restrictive cardiomyopathy
Somatic mutation
Increased spleen size
No previous family history
Venous thrombosis
Blood clot in vein


When the term hypereosinophilic syndrome (HES) was originally coined in 1975, the condition was thought to be 'idiopathic' or of an unknown cause. Today, in approximately 3/4 of cases, the underlying cause still remains unknown. However, recent advances in diagnostic techniques have lead researchers to believe that some people affected by HES may have eosinophilia due to a variety of causes, including:[2][4]

  • Myeloproliferative neoplasms or other disorders that affect the bone marrow (myeloproliferative disorders). This form is called myeloproliferative HES.
  • Increased production of interleukin-5 (a protein produced by certain types of white blood cell). This form is called lymphocytic HES.
  • A change (mutation) in an unknown gene passed down through a family. This form is called familial HES.


A diagnosis of hypereosinophilic syndrome is based on the following criteria:[1][2][3]

  • Persistent eosinophilia, as defined by blood counts showing increased numbers of eosinophils (greater than 1500 eosinophils/uL) for at least 6 months
  • Signs and symptoms of organ involvement
  • No evidence of other conditions that can cause eosinophilia*

*Due to advances in the diagnostic techniques, a specific cause of eosinophilia can be identified in a proportion of cases that would have otherwise been classified as idiopathic hypereosinophilic syndrome


The treatment and management of hypereosinophilic syndrome (HES) varies based on the severity of the condition and if an underlying cause for the high levels of white blood cells (eosinophilia) has been identified. Medications have been developed that target specific causes of HES. For HES without an identified cause, treatment is focused on managing the symptoms.[5]

Specialists involved in the care of someone with HES may include:

  • Hematologist
  • Oncologist
  • Immunologist
  • Infectious disease specialist
  • Cardiologist
  • Pulmonologist

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    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.

    Where to Start

      In-Depth Information

      • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
      • 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. 
        idiopathic hypereosinophilic syndrome
        familial eosinophilia
      • 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 Hypereosinophilic syndrome. Click on the link to view a sample search on this topic.


        1. Noh HR, Magpantay GG. Hypereosinophilic syndrome. Allergy Asthma Proc. January 2017; 38(1):78-81.
        2. Curtis C, Ogbogu P. Hypereosinophilic Syndrome. Clin Rev Allergy Immunol. April 2016; 50(2):240-251.
        3. Venkata Anuradha Samavedi, MBBS, MD. Hypereosinophilic Syndrome. Medscape Reference. March 2017; https://emedicine.medscape.com/article/202030-overview.
        4. Hypereosinophilic syndrome. Orphanet. January 2015; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=168956.
        5. Klion A. Hypereosinophilic syndrome: approach to treatment in the era of precision medicine. Hematology Am Soc Hematol Educ Program. Nov 30, 2018; 2018(1):326-331. https://pubmed.ncbi.nlm.nih.gov/30504328.
        6. Shomali W, Gotlib J. World Health Organization-defined eosinophilic disorders: 2019 update on diagnosis, risk stratification, and management. Am J Hematol. Oct 2019; 94(10):1149-1167. https://pubmed.ncbi.nlm.nih.gov/31423623.

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