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What exactly are rare diseases?

Also known as orphan diseases (orphan = one without parents; rare = seldom)

Whether a disease is defined as a rare disease depends on the frequency of its occurrence in the population. However, from the global point of view the definition is not consistent. 

Thus, in Europe those diseases that occur in less than 5 per 10,000 residents are defined as rare diseases.

Univ. Prof. Irene Lang, MD

Global figures

Less than 230,000 patients per year or 5 per 10,000 residents
Less than 200,000 patients per year or 7.5 per 10,000 residents
Less than 50,000 patients per year or 4 per 10,000 residents
Less than 2,000 patients per year or 1 per 10,000 residents

Dr. Rainer Riedl | Chairman of Debra Austria

What are the special features of RARE DISEASES?

Nearly all genetic disorders are rare diseases, but not all rare diseases are caused by genetic factors. Rare diseases include, for instance, some very rare infectious diseases, rare forms of autoimmune disorders, and even rare cancers.

Most causes of rare diseases have not been explained yet.

For many diseases the first symptoms may occur shortly after birth or in early childhood. In around 50% the first symptoms occur in adulthood.

Characteristics of rare diseases

  • Around half of the diseases occur in children; nearly all are caused by genetic factors
  • Many rare diseases are nearly unknown; very few specialists exist for these
  • The pathway to the correct diagnosis is tedious and frequently spans a period of several years
  • For the majority of the diseases (more than 95%) there are, to date, no specific therapy options.

Many rare diseases are life-threatening or very burdensome

About 26% of the patients die before they reach the age of five years.
About 37% have a reduced life expectancy, depending on the severity of the disease.
Only about 37% have a normal life expectancy

Specific Difficulties & Problems

Generally the patients struggle to accept their suffering, get competent medical care, and even social security. The difficulties lie mainly in the fields of diagnosis, the availability of relevant information, and finding suitable experts.

Lengthy Process of Diagnosis

> 6.000
More than 6,000 known rare diseases
> 6.000
The frequency of the individual rare diseases is relatively low, but this is contrasted by a wide spectrum of diverse disease patterns. The symptoms of rare diseases may differ widely in terms of severity, and the course of disease also varies significantly. Notably, several organs are affected simultaneously. Therefore the majority of rare diseases prove to be multi-system diseases.

Many rare diseases have not been sufficiently investigated so far to permit their unequivocal diagnosis at an early point in time. The time until the establishment of a reliable diagnosis is measured here not in weeks or months; some patients wait for several years. Quite frequently the patients are confronted with a series of false diagnoses due to the incorrect interpretation of their symptoms.

Priv.Doz. Dr. Stefan Seidel

"The time period from the onset of symptoms to the diagnosis may be 5 years or even 10 years for narcolepsy. To my knowledge, the longest period of diagnosis for this condition was 40 years."

Dr. Rainer Riedl Chairman of DEBRA Austria

"In the case of my daughter who has Epidermolysis bullosa, the clinical diagnosis took several months – and the exact diagnosis took as long as 14 years."

Living and Everyday Life with Rare Diseases

Many family members and especially social associates cannot imagine what a rare disease is and how it will progress. How they deal with the ill person and offer the person help in his/her daily life is a special challenge. Therefore, specialists who are able to offer the patient information about the course of the disease and therapy options are a great source of support.

Difficult to Access Specialists

The patients are frequently dependent on a very small number of specialists. In many cases the access to the specialists is rendered difficult by spatial distance; the patient may not be aware of the required expertise and the necessary specialised facilities or these may not be easy to find.

Patient organisations and self-help groups are a valuable means of exchanging experience among patients. A few patients desire more intensive exchange of experience with others, whereas others desire a more intensive doctor-patient relationship. The organisations take care of the Rare Disease Community while taking the patients‘ personal privacy into account.

Aspects of Therapy

Persons affected by rare diseases are frequently confronted with unsatisfactory therapy options or yet unapproved treatments. In many cases, suitable nursing measures can improve the patients‘ quality of life and also enhance their life expectancy. In part, impressive progress has been made in the treatment of some diseases. This shows that research work is not in vain; energy and resources should be invested in the targeted research of rare diseases.

No treatments exist for
95% of rare diseases
No treatments exist for 95% of rare diseases
Importantly, patients with rare diseases must have access to the treatments. Quite often they have to deal with exceptional bureaucratic hurdles such as bearing the costs of their treatment themselves, which are the result of ambiguous competences and jurisdictions.

Development under the burden of barriers

The development of ideas and solutions in the field of rare diseases requires an international network. Only by combining know-how is it possible to define fields of action and introduce lasting measures.

How does the European Union deal with RARE DISEASES?

The EU regulation on drugs for the treatment of rare diseases came into force on 22 January 2000. Its purpose was to promote the research, development, and dissemination of medical products for rare diseases.

The rising numbers of orphan drugs (drugs that have been specifically developed for the treatment of rare diseases) show that companies like AOP Health are actively and increasingly focussed on the field of rare diseases. About 20% of the drugs approved in the EU every year are orphan drugs.

Networking the existing expertise on specific disease patterns of rare diseases, on the basis of specialised centres, is of crucial importance. Also the research and development of therapy options can be improved and achieved more swiftly by these measures.


European Medicines Agency (EMA) at: https://www.ema.europa.eu/en/human-regulatory/overview/orphan-designation-overview, retrieved on 9.1.2019

Pharmig | Association of the Pharmaceutical Industry of Austria at http://www.pharmig.at/DE/Der%20Verband/Fachbereiche/Seltene%20Erkrankungen/Seltene+Erkrankungen.aspx, retrieved on 9.1.2019

Interview with Dr. Rainer Riedl on 29.11.2018

Interview with Univ. Prof. Irene Lang, MD, on 15.11.2018

Interview with Ass.-Prof. Priv.-Doz. Dr. Stefan Seidel on 30.10.2018


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