About Rare Diseases About Rare Diseases

About Rare Diseases

What is a rare disease?  

"Rare diseases" are diseases that affect a small number of people compared to the general population, and specific problems that arise in relation to the rarity of these diseases. In Europe, diseases which affect 1 in 2,000 people are considered to be rare. Approximately 50% of the patients consist of children. 30% of children with rare diseases cannot survive until the age of 5. The main reason for this situation is that 95% of rare diseases are untreatable. 

A disease can be rare in one region, but common in another. For example, thalassemia, a type of anemia of genetic origin, is rare in Northern Europe but common in the Mediterranean region. There are also many common diseases whose variants are rare.

Türkiye is one of the countries with common rare diseases mostly (80%) attributed to a genetic cause. Many genetic rare diseases with recessive inheritance are more common in our country than in Europe and the USA, because one in five marriages in our country is still consanguineous. It is estimated that approximately 6-7 million people in our country have rare diseases. Rare Diseases with no treatment options may result in a chronic, progressive and life-threatening condition if early diagnosis and treatment are not performed.


How many rare diseases are there?

There are thousands of known rare diseases. To date, eight thousand rare diseases have been discovered in the literature and these diseases are regularly described in the medical literature. The number of rare diseases also depends on the accuracy of the definition of the factors leading to the disease. Until now, in the field of medicine, a 'disease' has been defined as the alteration of the health condition, presenting as a unique pattern of symptoms with a single treatment. Whether a pattern is unique or not depends entirely on the accuracy of our analysis.


What are the origins and characteristics of rare diseases?

Almost all genetic diseases are rare diseases; however, not all rare diseases are genetic diseases. For example, there are very rare infectious diseases as well as autoimmune diseases and rare cancers.

Rare diseases are serious, mostly chronic and progressive diseases. For many rare diseases such as proximal spinal muscular atrophy, neurofibromatosis, osteogenesis imperfecta, chondrodysplasia or Rett syndrome, symptoms can be observed at birth or in childhood. However, more than 50% of rare diseases (e.g. Huntington’s disease, Crohn's disease, Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis, Kaposi's sarcoma or thyroid cancer) appear during adulthood.


What are the medical and social consequences of the rarity of these diseases?

The field of rare diseases suffers from a deficit of medical and scientific knowledge. For a long time, doctors, researchers and policy makers were unaware of rare diseases and until very recently there was no real research or public health policy concerning issues related to this field. There is no cure for most rare diseases, but the appropriate treatment and medical care can improve the quality of life of patients and extend their life expectancy. Impressive progress has already been made for certain diseases, which shows that we must not give up the fight, but on the contrary, continue and step up efforts in the fields of research and social solidarity.

Those affected by these diseases all face similar difficulties in their quest for a diagnosis, relevant information and proper direction towards qualified professionals.  Specific issues are equally raised regarding access to quality healthcare, overall social and medical support, effective liaison between hospitals and general practices, as well as professional and social integration and independence.
People affected by rare diseases are also more psychologically, socially, economically and culturally vulnerable. These difficulties could be overcome by appropriate policies. Due to the lack of sufficient scientific and medical knowledge, many patients are not diagnosed. Their disease remains unidentified. These are the people who suffer the most from difficulties in receiving appropriate support.

What progress is foreseen in the diagnosis and treatment of rare diseases?

For all rare diseases, science can provide some answers. Hundreds of rare diseases can now be diagnosed through a biological sample test. More knowledge of the natural history of these diseases is obtained by the creation of archives for some of them. Researchers are increasingly working through networks in order to share the results of their research and to advance more efficiently.  New hopes arise with the perspectives offered national policies in many countries in the field of rare diseases.


Where can I find information about a specific disease?

Orphanet provides inventory of rare diseases and information on more than 6000 of these diseases, as well as a guidance on specialized services in Europe.