February 28: world day of rare diseases, more common than we think

What are considered rare diseases?

Rare diseases are generally considered to be those diseases that have a low prevalence in the population. Depending on the region, different prevalence have been established to consider a disease as rare, for example, the European Union has considered a prevalence of 5 per 10,000 people to consider a disease as rare. Other countries have more restrictive criteria, such as Japan, where diseases with less than 4 cases per 10,000 habitant are considered rare, or the United States, where a disease is considered rare if less than 200,000 cases are described in the whole country.

According to the World Health Organization (WHO), nearly 7,000 rare diseases have been already described and to this day, more diseases continue to be described in the scientific literature. Therefore, although each of these diseases affects a small group of people, the total number of people affected by a rare disease is around 7% of the population. For example, in Spain it is estimated that there are more than 3 million people affected by a rare disease.

What are the characteristics of rare diseases?

Most rare diseases are severe, chronic, progressive and usually appear in paediatric age, although some diseases are diagnosed in adulthood. In general, there is a higher prevalence in adulthood due to excess infant mortality among those affected by rare diseases.

At least 75% of rare diseases have a genetic origin, the rest of the causes being very diverse, for example, there are autoimmune diseases, some types of cancers or infectious diseases that are very infrequent.

What does it mean to be affected by a rare disease?

The diagnosis of a rare disease can take years and sometimes they are diagnosed incorrectly due to the lack of knowledge of these pathologies. On average, it takes a patient 4 years to obtain a diagnosis. In 31% of cases, the lack of diagnosis causes a worsening of the disease symptoms that could have been avoided with an early diagnosis. This lack of diagnosis also often hinders treatment for rare diseases, causing up to 42.68% of patients to have no treatment or to receive inadequate treatment.

People affected by rare diseases often see their life quality affected, as these kind diseases often cause chronic pain, physical or intellectual disabilities or senses impairment such as blindness or or deafness.

What initiatives exist for the visualization of these diseases?

The European Organization for Rare Diseases (EURORDIS) celebrates the Mundial day for Rare Diseases on February 28th, with the aim of raising awareness of these diseases and the need for research to be put into them.

In Spain, the Spanish federation of rare diseases (FEDER) has as a task “To represent and defend the rights of people with a rare disease and suspected diagnosis, favouring their inclusion and generating strategies that contribute to improve their quality of life.”

Currently, carrier screening tests aim to reduce the risk of having a child affected by the most prevalent genetic rare diseases with a known cause. By determining the healthy carrier status of forthcoming parents and determining the risk of having a child affected by one of the diseases screened for. If a high risk is detected, couples can decide alternatives such as preimplantation diagnosis, prenatal diagnosis or early diagnosis from birth, facilitating the application of appropriate treatment.