How Rare A Rare Disease Can Be?

As the name already clearly suggests, rare diseases are uncommon. The definition of "rare disease", however, varies across the globe. In the European Union, a rare disease is defined as a life-threatening or chronically debilitating condition that affects not more than five persons per ten thousand.

In the USA, on the other hand, a disease is called "rare" when it affects less than 200,000 of the country’s inhabitants. Irrespective of the precise definition, each rare disease is known as such because of the limited number of individuals that suffer from it. However, as a whole, rare diseases have quite a high prevalence. How this can be possible? Delve into the fascinating world of rare diseases with us, and discover what's being done to help people who suffer from them.

Rare diseases are not as uncommon as you might think

This means that 400 million people all over the globe, with about 30 million in Europe and 25 million in the United States, are affected by a very uncommon disease. The vast majority of these medical conditions (about 80 percent) have a genetic basis, with one or more known genes involved. The other 20 percent include rare infectious diseases, auto-immune diseases or rare poisonings that are seldom identified.

Few rare diseases are known to general public

Despite their low frequency, several rare diseases are actually known to the general public. Examples of more known rare diseases include cystic fibrosis, haemophilia and phenylketonuria. Others, however, are rare not only in their prevalence but also in their public awareness. For instances:

• Primary ciliary dyskinesia is an inherited disease that causes the tiny, hair-like structures of the airways (cilia) to not move as they normally would. This leads to an accumulation of bacteria, dust and other small particles in the airways, causing serious breathing problems from the moment of birth.
• Progeria is a congenital disease that leads affected individuals to essentially present with signs and symptoms of premature aging at a very rapid rate. Profound growth delays begin at between nine and 24 months, leading to abnormal facial developments such as a disproportionately small face, bulging, prominent eyes and an underdeveloped jaw. By the age of two, hair from the scalp, eyebrows and eyelashes is lost. Many progeria sufferers eventually lose the layer of fat beneath the skin and, in time, elasticity is lost in the artery walls, leading to fatality via heart attack or stroke.
• Mobius syndrome is an extremely rare, genetic neurological condition. Sufferers cannot close their eyes, look from side to side, or form facial expressions. Limb abnormalities such as clubbed feet and missing fingers are often also present. Due to the importance of facial expression and smiling in social interaction, the inability to form either can lead individuals with Möbius being perceived as unhappy, unfriendly or uninterested in conversations.

Some rare diseases are especially frequent within a particular region or within a specific group of people. For example, thalassaemia is more frequent in the Mediterranean area than in Northern Europe. Gaucher disease is quite frequent in the Ashkenazi Jewish population.

The low prevalence of rare diseases leads to neglect in research

So, even though individually they are uncommon, rare diseases as a category are actually ubiquitous in nature. However, it is their relatively low prevalence that has caused rare diseases to have been generally neglected by the scientific, medical and political communities. Knowledge and awareness of most of the diseases is scarce, and sometimes even completely non-existing.

See Also: Neglected And Orphan Diseases Call For Governments' Intervention

In fact, many patients go completely undiagnosed and the medical and social consequences for them and their families are often devastating.

Drugs For Rare Diseases Do Get Developed, Although Not Fast Enough

Most rare diseases, even when well characterized, simply cannot be treated. This is because pharmaceutical companies are not interested in developing drugs for these disorders, mainly because the return on the enormous investment needed to develop a pharmaceutical product for a rare disease is not attractive for these companies. This regrettable situation remained largely unchanged for many years, and it was only in the past few decades that orphan diseases gained recognition as a serious public health problem, thanks to the activism of patients’ associations and professional groups.

Starting in the 1980s in the USA, efforts have been made to stimulate the research, development and marketing of medicinal products for rare diseases. Nowadays, regulatory incentives exist in most developed countries, with policies on orphan drugs being adopted in Japan, Australia and EU in the 1990s and 2000s. 

In addition, the establishment of various research programs and networks has also helped to advance scientific understanding and improve diagnosis rates of rare diseases. For instance, the International Rare Diseases Research Consortium (IRDiRC) was launched in 2011 at the initiative of the European Commission and the U.S. National Institutes of Health with the aim of fostering international collaboration in rare disease research.

Finding reliable information for rare diseases can be problematic

However, despite these positive developments, the burden of rare diseases continues to persist.

See Also: Rare Condition: Leprosy (Hansen's Disease)

Many turn to quick Internet searches, but most sources fail to be reliable and can actually raise unjustified concerns and beliefs. It is crucial to avoid articles written by laypeople, as this can lead to the mismanagement of symptoms. Sources of detailed, quality-assured information on rare diseases include the following:

• EURORDIS InfoHub: EURORDIS is a European non-governmental patient-driven alliance of patient organizations and individuals active in the field of rare diseases. Their InfoHub page (http://www.eurordis.org/rare-disease-information) helps patients to find quality rare disease information on the Internet, indicates where to find quality rare disease information on the Internet, and includes a tool to provide access to search results based on an index of affiliated patient organization websites.
• Office of Rare Diseases Research: the website of the ORDR, which belongs to the U.S. National Center for Advancing Translational Sciences , offers visitors a very complete resource  page. From here, patients will be guided to a series of reliable websites on various topics related to rare diseases, including rare disease social networks, online medical reference Web sites, rare disease events, and more (http://rarediseases.info.nih.gov/resources/2/rare-diseases-resources).
• ORPHANET: Orphanet is s the reference portal for information on rare diseases and orphan drugs (http://www.orpha.net/). It is perhaps one of the most complete online sources on information about rare diseases, including an inventory of rare diseases and an inventory of orphan drugs at all stages of development.