Rare diseases, which until recently concerned the scientific community due to their uniqueness and complex medical management, now appear in many cases to be no longer so… rare.

Indeed, data show a nationwide increase in cases across several categories of diseases that were previously classified in the Ministry of Health’s “rare disease lists,” while in some cases their incidence has even doubled within just a few years. At the same time, scientists around the world are discovering a new rare disease every other day.

Of course, diagnosis of rare diseases is now easier thanks to new tools and genetic testing (which partly explains the increase in numbers). However, data also reveal that in many cases a different medical and operational approach is now required from modern healthcare systems.

It is indicative that while a decade ago a disease was considered rare if it affected 1 in 10,000 people, this threshold has now shifted to 1 in 2,000.

Which rare diseases are no longer rare

A classic example of increasing incidence is Crohn’s disease, a chronic inflammatory disease of the digestive tract. When first identified it was considered rare, but the number of diagnosed cases has now led to its “declassification” as a rare disease.

Other conditions, such as spinal muscular atrophy and cystic fibrosis, are also no longer as rare as they once were.

Data show that more than 300 million people worldwide are affected by a condition that remains undiagnosed or unclassified, while the total number of rare diseases identified to date is estimated at over 7,000.

In most cases, these diseases are attributed to a “faulty” gene, with half of today’s patients being children.

Living with a rare disease

Hermis is one of these children. He was diagnosed with a particularly rare neurological disease about 14 years ago, when he had just completed his first year of life. His father, Dimitris Athanasios, tells Vima that the diagnosis came by chance, after the baby was briefly hospitalized with gastroenteritis symptoms. Following specific tests, it was found that the child suffers from Duchenne disease.

“Daily life with a child with Duchenne is full of love, but also constant responsibility,” his father says today. “There are physiotherapy sessions, medical appointments, monitoring of cardiac and respiratory indicators, adjustments at school. But there is also a deep awareness that time carries a different weight. In some rare diseases, delays in access to treatment can mean a loss of function that cannot be regained.”

He himself is now vice-president of ESAMEA – National Confederation of Persons with Disabilities– and closely follows developments in data and policy management.

In the case of Duchenne muscular dystrophy, however, the picture is reversed, with a global decrease in cases. It is estimated that the ratio of 1 case per 3,500 male births has fallen to 1 in 7,000, as suspicion of the hereditary basis helps prevent new births of affected children.

Increase in diagnoses in Greece

In recent years, the landscape of rare diseases has been changing at a pace previously considered unimaginable. For decades, patients in Greece—estimated at around half a million—along with their families, faced a painful and often dead-end journey toward diagnosis. Today, however, advances in genetics, new technologies, and strengthened international cooperation are reshaping the field.

Mr. Athanasios explains that “today, with gene sequencing technologies, we can identify many more diseases.” Prenatal and preventive genetic testing has also now been integrated into everyday medical practice.

Today, it is estimated that there are around 7,000 to 8,000 recorded rare diseases in the country, most of which have a genetic basis. These are conditions with very low prevalence, often less than 1 in 2,000 people, and in some cases as rare as 1 in a million.

The role of international cooperation

In this rapidly evolving environment, international cooperation emerges as a decisive factor. Alexis Arzimanoglou is a professor and coordinator of the European Reference Networks (ERN), an initiative of the European Union aimed at improving diagnosis and care.

“The need for early and accurate diagnosis, equal access to treatments, and placing the patient at the center of care are fundamental principles,” he says in an interview with Vima. ERNs represent a unique model of collaboration, connecting hundreds of hospitals and specialized units across Europe. This allows doctors to consult experts in other countries, exchange data, and jointly assess complex cases.

However, despite progress, Greece continues to face challenges. There are specialized centers and significant scientific expertise, but coordination between structures is not always sufficient. Patients often have to go through multiple stages before reaching the appropriate specialist. In Greece, there are 44 centers of expertise and more than 200 specialized clinics, but this is still not enough.