According to the European Union on Public Health, rare diseases are defined as 5 cases per 10,000 people (.05%).^1,2They are often time life-threatening or chronically debilitating.

The National Institutes of Health (NIH) in the United States defines rare diseases similarly, as those "generally considered to have a prevalence of fewer than 200,000 affected individuals …."³ This translates to a prevalence of roughly .07%, considering that the US population is approaching 300 million.⁴

Despite the extremely low incidence and prevalence of such disorders, their impact is profound. For affected patients, many rare disorders result in substantial morbidity and reduced quality of life. They represent a heavy economic burden for patients and their families, and may often lead to death at a very young age. In addition, by virtue of their low prevalence, information on the diagnosis and treatment of rare diseases is often sparse. Thus, expert medical care might not be available and patients do not benefit from the resources and services they need.¹

The purpose of this website is to provide health professionals with information on 4 rare diseases which have a common link—alterations in platelet derived growth factor receptor (PDGFR) and cKIT. PDGFR and cKIT are receptors with tyrosine kinase activity and are responsible for cell growth and division. These 4 rare diseases are:

• Dermatofibrosarcoma protuberans (DFSP)
• Hypereosinophilic syndrome (HES)
• Mast cell disease (mastocytosis)
• Myeloproliferative/myelodysplastic disorders
  • Chronic myelomonocytic leukemia (CMML)
  • Atypical chronic myeloid leukemia (aCML)
  • Juvenile myelomonocytic leukemia (JMML)

Click on the options listed for useful information about the diagnosis of these disorders, current treatment options, informational resources, and current clinical trials of investigational therapies.

Myelodyplastic Myeloproliferative Diseases

References :

1. The European Union On-Line. Public Health.Available at: http://europa.eu.int/comm/health/ph_threats/non_com/
rare_diseases_en.htm Accessed April 25, 2006.

2. Rare Cancer Alliance.Available at: http://www.rare-cancer.org/rare-diseases.html. Accessed April 24, 2006.

3. National Institutes of Health. Office of Rare Diseases. Available at:http://ord.aspensys.com/asp/diseases/diseases.asp. Accessed April 24, 2006.

4. U.S. Census Bureau. Available at: http://www.census.gov. Accessed April 24, 2006.