Hypereosinophilic syndrome

What causes hypereosinophilic syndrome?

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:

  • 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.

Last updated on 05-01-20

How is hypereosinophilic syndrome diagnosed?

A diagnosis of hypereosinophilic syndrome is based on the following criteria:

  • 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

Last updated on 05-01-20

Is hypereosinophilic syndrome inherited?

Although most cases of hypereosinophilic syndrome (HES) are not inherited, some cases do appear to be passed down through a family. In these families, the exact underlying genetic cause is unknown, but the genetic change (mutation) is thought to be inherited in an autosomal dominant manner.

In autosomal dominant conditions, an affected person only needs a change (mutation) in one copy of the responsible gene in each cell. In some cases, an affected person inherits the mutation from an affected parent. Other cases may result from new (de novo) mutations in the gene. These cases occur in people with no history of the disorder in their family. A person with an autosomal dominant condition has a 50% chance with each pregnancy of passing along the altered gene to his or her child.

Last updated on 05-01-20

How might hypereosinophilic syndrome be treated?

The treatment and management of hypereosinophilic syndrome (HES) varies based on the severity of the condition and if an underlying cause for the eosinophilia has been identified. For example, in people with myeloproliferative HES who have a somatic gene deletion leading to the FIP1L1/PDGFRA fusion gene, imatinib is the drug of choice.

Affected people without the FIP1L1/PDGFRA fusion gene are typically treated with corticosteroids initially. Approximately one third of these cases do not respond to steroids so other agents, such as hydroxyurea, interferon- alpha, and imatinib, may be administered.

In people who are affected by HES that do not respond to standard treatments, other therapies may be tried, including chemotherapy and hematopoietic stem cell transplantation; however, there is little data regarding the effectiveness of these treatments so they are not routinely given.

Last updated on 05-01-20

Name: American Partnership For Eosinophilic Disorders PO Box 29545
Atlanta, GA, 30359, United States
Phone: 713-493-7749 Email: mail@apfed.org Url: http://www.apfed.org
Name: International Eosinophil Society 555 East Wells Street, Suite 1100
Milwaukee, WI, 53202, United States
Phone: 414-276-6445 Email: info@eosinophil-society.org/ Url: http://www.eosinophil-society.org/
Name: Cincinnati Center for Eosinophilic Disorders United States Phone: 513-636-2233 Toll Free: 800-344-2462 Email: cced@cchmc.org Url: http://www.cincinnatichildrens.org/service/c/eosinophilic-disorders/default/

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The RareGuru disease database is regularly updated using data generously provided by GARD, the United States Genetic and Rare Disease Information Center.

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