Know All About Rare Disease, Causes And Characteristics

What is a Rare Disease?

There are over 300 million people living with one or more of over 6,000 identified rare diseases around the world1, each supported by family, friends and a team of carers that make up the rare disease community.

Each rare disease may only affect a handful of people, scattered around the world, but taken together the number of people directly affected is equivalent to the population of the world’s third largest country.

Rare diseases currently affect 3.5% - 5.9% of the worldwide population. 72% of rare diseases are genetic whilst others are the result of infections (bacterial or viral), allergies and environmental causes, or are degenerative and proliferative. 70% of those genetic rare diseases start in childhood.

A disease defined as rare in Europe when it affects fewer than 1 in 2,000 people.

Characteristics of rare diseases

Over 6000 rare diseases are characterised by a broad diversity of disorders and symptoms that vary not only from disease to disease but also from patient to patient suffering from the same disease.

Relatively common symptoms can hide underlying rare diseases leading to misdiagnosis and delaying treatment. Quintessentially disabling, the patients quality of life is affected by the lack or loss of autonomy due to the chronic, progressive, degenerative, and frequently life-threatening aspects of the disease.

The fact that there are often no existing effective cures adds to the high level of pain and suffering endured by patients and their families.

Common chaellenges

The lack of scientific knowledge and quality information on the disease often results in a delay in diagnosis. Also the need for appropriate quality health care engenders inequalities and difficulties in access to treatment and care. This often results in heavy social and financial burdens on patients.

As mentioned, due to the broad diversity of disorders and relatively common symptoms which can hide underlying rare diseases, initial misdiagnosis is common. In addition, symptoms differ not only from disease to disease, but also from patient to patient suffering from the same disease.

Due to the rarity and diversity of rare diseases, research needs to be international to ensure that experts, researchers and clinicians are connected, that clinical trials are multinational and that patients can benefit from the pooling of resources across borders. Initiatives such as the European Reference Networks (networks of centres of expertise and healthcare providers that facilitate cross-border research and healthcare), the International Rare Disease Research Consortium and the EU Framework Programme for Research and Innovation Horizon 2020 support international, connected research.

How can Rare Disease Day make a difference?

Rare Disease Day raises awareness for the 300 million people living with rare disease around the world and their families and carers. The long-term cause of the Rare Disease Day campaign is to achieve equitable access to diagnosis, treatment, health and social care and social opportunity for people affected by a rare disease.

Important progress continues to be made with joint international advocacy efforts for universal health coverage (UHC), part the United Nation’s Sustainable Development Goals (SGDs) to advocate for equitable health systems that meet the needs of people affected by rare diseases in order to leave no one behind.

Rare Disease Day is the opportunity advocate for rare diseases as a human rights priority at local, national and international level as we work towards a more inclusive society.

Rare Disease Day is a great example of how progress continues to be made, with events being held worldwide each year. Beginning in 2008, when events took place in just 18 countries, Rare Disease Day has taken place every year since, with events being held in over 100 countries in 2019.

How many rare diseases are there?

There may be as many as 7,000 rare diseases. The total number of Americans living with a rare disease is estimated at between 25-30 million. This estimate has been used by the rare disease community for several decades to highlight that while individual diseases may be rare, the total number of people with a rare disease is large.

In the United States, only a few types of rare diseases are tracked when a person is diagnosed. These include certain infectious diseases, birth defects, and cancers. It also includes the diseases on state newborn screening tests. Because most rare diseases are not tracked, it is hard to determine the exact number of rare diseases or how many people are affected.

If you are looking for statistics on a specific disease, check to see if the disease is listed in MedlinePlus Genetics or GeneReviews. These resources usually include statistical information. To find medical journal articles with statistics, you can conduct a PubMed search using the disease name and the word "prevalence" or "incidence."

What causes rare diseases?

There are many different causes of rare diseases. The majority are thought to be genetic, directly caused by changes in genes or chromosomes. In some cases, genetic changes that cause disease are passed from one generation to the next. In other cases, they occur randomly in a person who is the first in a family to be diagnosed.

Many rare diseases, including infections, some rare cancers, and some autoimmune diseases, are not inherited. While researchers are learning more each year, the exact cause of many rare diseases is still unknown.

What is being done to develop treatments for rare diseases?

Researchers have made progress in learning how to diagnose, treat, and even prevent a variety of rare diseases. However, there is still much to do because most rare diseases have no treatments.

The National Institutes of Health (NIH) supports research to improve the health of people with rare diseases. Many of the 27 Institutes and Centers at the NIH fund medical research for rare diseases. One of these Centers, the National Center for Advancing Translational Sciences (NCATS), focuses on getting new cures and treatments to all patients more quickly. NCATS supports research through collaborative projects to study common themes and causes of related diseases. This approach aims to speed the development of treatments that will eventually serve both rare and common diseases.

The NCATS Office of Rare Diseases Research (ORDR) guides and coordinates NIH-wide activities involving research for rare diseases. Some of the NCATS programs for rare diseases include:

• Rare Diseases Clinical Research Network (RDCRN)
• Therapeutics for Rare and Neglected Diseases (TRND)
• Rare Diseases Registry Program (RaDaR)
• Genetic and Rare Diseases Information Center (GARD)

Efforts to improve and bring to market treatments for rare diseases are coordinated by the Food and Drug Administration (FDA). The Office of Orphan Products Development (OOPD) provides incentives for drug companies to develop treatments for rare diseases. Between 1973 and 1983, fewer than 10 treatments for rare diseases were approved. Since 1983, the OOPD program has helped develop and bring to market more than 400 drugs and biologic products for rare diseases.