Rare diseases: the importance of a correct diagnosis

Rare diseases (RD) or minority diseases are those that have a low prevalence in the population. To be considered rare, each specific disease can only affect a limited number of people. Specifically, when it affects less than 5 out of every 10,000 inhabitants.

However, rare pathologies affect a large number of people, since according to the World Health Organization (WHO), there are about 7,000 rare diseases affecting 7% of the world’s population. In total, it is estimated that in Spain there are more than 3 million people with rare diseases.

What is the cause of rare diseases?

Most rare diseases are genetic in origin. Although not all of them have this cause, there are very rare infectious diseases, or autoimmune diseases or tumors whose exact etiology is unknown.

When should a rare disease be suspected?

It is necessary to have the suspicion that a patient may have a rare disease, if the following characteristics are present:

  • Symptoms that begin in childhood or adolescence. Although it is also possible that some rare diseases manifest themselves in adulthood.
  • Family history of a rare disease, or family history of a certain pattern of symptoms. For example: joint hypermobility, mental retardation, periodic fevers, frequent bone fractures, etc.
  • Deficits in motor, sensory or intellectual development that may lead to disability.
  • Multiple organ involvement: skin, bone, liver, heart, kidneys, etc.
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What are the main problems of patients with rare diseases?

The main problem encountered by patients with rare diseases is the correct diagnosis of their disease. Normally patients go through multiple specialists before a correct diagnosis is reached. This happens because of the lack of information on these diseases, the lack of training of doctors in these types of pathologies and the difficulty in finding doctors or centers specializing in rare diseases.

This delay in diagnosis negatively affects both the patient and the family, due to the stressful situation generated by not knowing what is wrong with the affected person and the delay in therapeutic interventions that can lead to a worsening of the patient’s clinical situation.

Do you foresee an improvement in the diagnosis and treatment of rare diseases?

Given the progress of science today, when a rare disease of genetic origin is suspected, diagnosis is relatively easy by performing specific genetic tests. These tests, which some time ago were inaccessible to the majority of the population due to their price, have become much cheaper in recent years thanks to the appearance of genetic analysis techniques called massive gene sequencing.

With regard to treatment, some rare diseases, such as Gaucher disease, Fabry disease or Hereditary Amyloidosis (to give some examples), currently have effective treatments that improve the prognosis and quality of life of patients. However, with the emergence of genetic therapies, it is expected that in a few years the therapeutic outlook for rare diseases of genetic origin will change radically for the better. Many of these diseases may even be cured.