Health. Rare diseases, not that so rare ...

They affect nearly 3 million people in France and there are nearly 7,000 different. The so-called rare diseases are 80% of genetic origin. Professor Sylvie Odent, from the "Genetics of Developmental Pathologies" (GPLD) team, also runs a specialized service in Rennes at the University Hospital Center.


Trisomy 21, bicycle-palatal cleft, chronic lymphocytic leukemia with B cells, renal dysplasia, deletion syndrome, congenital toxoplasmosis, Smith-Magenis syndrome or Williams syndrome ... Some examples of so-called rare diseases. "That is to say, they affect less than one in 2,000, explains Professor Sylvie Odent, head of the department of medical genetics at the University Hospital of Rennes. There are nearly 7,000 and in France, they affect nearly 3 million people. "Rare diseases that are not so rare that even if some have only a few cases in the world.


Wandering diagnosis


"Thanks to advances in bioinformatics and new high-throughput sequencing techniques, we are now able to identify them more easily," says the professor. But it is still necessary that the carriers of rare diseases are sent to the right specialists to avoid what is called diagnostic wandering. "This is the most difficult point for patients. Between the onset of the first symptoms and the identification of the disease, it can happen years, "says Professor Odent.

Professor Sylvie Odent, head of the department of medical genetics at the University Hospital of Rennes and coordinator of the center of rare diseases. | OUEST-FRANCE


Clinical signs are not always easy to interpret by general practitioners or by other non-specialized health professionals, this wandering can be long, even very long. Which explains why almost half of patients do not have an accurate diagnosis. And who says no diagnosis, no suitable treatment!

A finding that dulls patient associations as 80% of rare diseases are of genetic origin and can be transmitted. "Unfortunately, today, there are only five prenatal tests that are performed while we could practice many more," says the hospital practitioner.


Disabling and disabling diseases

New high throughput sequencing techniques are expected to better diagnose rare diseases. | REUTERS

A wandering diagnosis that is not to be confused with the diagnostic impasse. "People are in the right place at the hands of good specialists, but we are not able to make a diagnosis. Here again, Professor Odent hopes that the development of new technologies will reduce this wandering. "We must not forget that these rare diseases can be very disabling and debilitating. Hence also the implementation of a third health plan to accelerate the diagnosis.

Finally, and this is the least of the problems, curative treatments remain relatively rare. Research laboratories are reluctant to invest huge sums of money for treatments for very specific diseases. Same difficulty to conduct research.

However, there is no question for Professor Odent and all his colleagues at European and global level to give up. Just like the world day of rare diseases which will take place, Thursday, February 28, on the subject of the health and the social protection.


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