Rare diseases are conditions that affect a relatively small proportion of the population. According to the definition used in the European Union, a disease is considered rare when it affects fewer than 5 people per 10 000. Because of this definition, the number of people affected by individual rare diseases is small, but globally there are more than 7 000 different rare diseases that affect millions of people worldwide.
The classification of rare diseases is complex as they cover a wide range of disorders and conditions, from genetically determined to infectious to autoimmune. Many of these diseases are chronic and progressive, meaning that patients require long-term care and support.
Statistically, rare diseases often go undiagnosed or are diagnosed late. It is estimated that in Europe and the United States together, rare diseases affect around 30 million people. It is worth noting that around 80% rare diseases have a confirmed genetic basis, making genetic testing a key element in their diagnosis.
Unraveling the mysteries of genetics and the environment in the context of rare diseases is like a detective investigation in the world of medicine. Although many rare diseases have a genetic basis, the pathways leading to their development are often complex and diverse.
In the maze of genes
A fundamental factor in the development of many rare diseases is genetic mutations. These are changes in DNA that can be inherited from parents or arise spontaneously. For inherited diseases, such as cystic fibrosis or haemophilia, tracing genetic patterns in families reveals recurring scenarios. On the other hand, spontaneous mutations, such as those found in Rett syndrome, can arise suddenly, with no previous family history of the disease.Advanced genetic research, such as whole genome sequencing, is uncovering new mutations and pathways that may contribute to rare diseases. These discoveries are not only expanding our knowledge of disease aetiology, but also opening the door to potential targeted therapies that may one day revolutionise treatment.
The role of the environment
Although genetics plays a key role, environmental factors also have a significant impact on the development of rare diseases. Exposure to certain chemicals, toxins and even certain viruses can contribute to the activation of a genetic predisposition to rare diseases. For example, research suggests that exposure to certain environmental factors may increase the risk of developing rare neurological conditions.
It is also interesting to note how our everyday environment and lifestyle can affect our genes - a process known as epigenetics. Epigenetic modifications can alter gene expression without changing the DNA sequence itself, which can influence the development of rare diseases.
The best-known rare diseases
Here are some of the best-known rare diseases:
- Cystic fibrosis - a genetic disease that affects the respiratory and digestive systems. It is characterised by the production of thick and sticky mucus that can clog the airways and pancreatic ducts.
- Haemophilia - an inherited blood disorder that causes problems with blood clotting. Patients with haemophilia may experience excessive bleeding even with minor injuries.
- Duchenne muscular dystrophy - a genetic disorder that causes progressive loss of muscle function. The disease usually manifests itself in childhood and leads to significant motor disability.
- Ehlers-Danlos syndrome - a group of connective tissue disorders characterised by elastic skin, excessive joint mobility and tissue fragility.
- Marfan syndrome - a genetic connective tissue disorder that affects the heart, eyes, blood vessels and skeleton. People with Marfan syndrome tend to be tall and slim, with long limbs and fingers.
Diagnosis
Diagnosing rare diseases is complicated by their diversity and non-specific symptoms, often leading to a long and frustrating process of 'itinerant diagnosis'. Key challenges include insufficient awareness among doctors and variable symptoms of diseases.
Technological advances, such as next-generation sequencing (NGS) and the use of artificial intelligence, are making it much faster and easier to identify the genetic causes of rare diseases. Global medical data integration and international collaboration also play a key role in improving the diagnosis of these conditions.
Thanks to these developments, patients can expect faster and more accurate diagnosis, which is crucial for appropriate treatment and improved quality of life.
Building awareness and education
Building global awareness and education about rare diseases is key to improving the lives of those affected. Increasing understanding of the challenges faced by patients and highlighting the importance of research and access to appropriate healthcare are fundamental elements in the fight against rare diseases.
Increasing public awareness is crucial, as many rare diseases are still poorly understood by both the public and medical professionals. Many people live with a misdiagnosis or without a diagnosis for years, leading to delays in accessing treatment and support.
Education is key to breaking down barriers to accessing care and treatment. Informing doctors, researchers and policy makers about rare diseases can lead to better diagnosis, faster diagnosis and more effective treatment options.
Working together for the future
Building a stronger, more united community of people affected by rare diseases is essential. Sharing stories and experiences can foster mutual understanding and solidarity, which is key to improving patients' lives.
Continuing research into rare diseases is also essential. Fostering innovation and scientific progress is key to developing new therapies and solutions that can revolutionise the lives of people with rare diseases.