Hypereosinophilic Syndrome (HES)

What is hypereosinophilic syndrome?

Hypereosinophilic (hy-per-ee-o-sin-o-FILL-ick) syndrome, also known as HES, is a rare blood disease in which the body produces too many of a particular type of blood cell called eosinophils (ee-o-SIN-o-fills). Eosinophils normally help the body fight allergies and certain types of infections.

People with HES might have different symptoms, depending on which parts of the body are affected. These symptoms may include:

• Tiredness
• Cough
• Shortness of breath
• Muscle pain
• A rash or rashes
• Fever

However, these symptoms are also common in many other medical conditions. Only medical testing can determine whether someone has HES.

 

How common is HES?

HES is very rare, and the exact number of cases is not known. In a city of 200,000 people, there might be only 1 or 2 new cases of HES each year. HES usually develops between the ages of 20 and 50. Nine out of 10 cases occur in males.

 

What causes HES?

The cause of HES is unknown. There are clues, though, that indicate it begins in a person's genes. Researchers have found that in some people with HES, 2 genes somehow combine to form a new combination gene. This "fusion gene" causes the body to make a protein known as a kinase (KY-nase), which causes some blood cells to multiply.

 

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