How many people live with MYT1L worldwide?

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As of January 2026, fewer than one hundred patients have been described in the international scientific literature, as stated in the official PNDS issued by the French National Authority for Health (HAS).

However, nearly 500 individuals are currently identified through international family networks, including around 80 families in France connected through the Les Extra-Vaillants MYT1L association. This gap reflects the considerable contribution of patient associations to identifying and registering affected persons.

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• A reality far greater than the data

These figures fall well below the actual epidemiological picture: the exact prevalence of MYT1L syndrome remains unknown. The rarity of diagnosis reflects the historical limits of screening rather than the true frequency of the condition.

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• An evolving landscape

Among younger patients, diagnoses are accelerating thanks to advances in genetic sequencing techniques (array-CGH, exome and genome sequencing), now more accessible and more precise. MYT1L syndrome is now better recognized and more quickly identified than just a few years ago.

However, many adolescents and adults still live with an unidentified neurodevelopmental condition, sometimes since childhood, without having undergone recent genetic exploration.

 

• 🧬 It is never too late to seek a genetic consultation

Regardless of age, a molecular diagnosis can be established. And even a late diagnosis is life-changing:

1. It puts a name on a journey often marked by uncertainty and unanswered questions

2. It opens access to the PNDS, reference centers, disability rights, and adapted support

3. It enables joining a community that understands, shares, and supports

4. It informs the family (genetic counseling, family planning)

If you, your adolescent child, or an adult close to you presents a never-explored or long-unexplored neurodevelopmental profile, speak to your general practitioner: they can refer you to a clinical genetics consultation.