A scientific article published in the Journal of the Neurological Sciences tends to show that Charcot’s disease, a neurodegenerative disease hitherto unexplained, is linked to toxins contained in a fungus frequently confused with morel.
Between 1990 and 2018, around fifteen cases of amyotrophic lateral sclerosis (ALS), also called Charcot disease, were diagnosed in the small village of Montchavin, in Savoie, in the French Alps. This high concentration of cases of this rare and fatal neurodegenerative disease challenges the medical world, especially as the various patients, aged 39 to 75, are unrelated.
After ten years of research, a Franco-American scientific team just established the link between these people. They would all have consumed on several occasions the same mushroom, the giant gyromiter (Gyromitra gigas), also called “false morel” for its resemblance to its cousin which is edible after drying or complete cooking, and in reasonable quantities.
Similar case in Guam, Pacific
At the origin of this hypothesis, we find a toxicologist from the University of Oregon, in the United States, Peter Spencer. The researcher had already investigated a similar situation in the 1990s on the island of Guam, in the Pacific.
The seeds of “Cycas revoluta”, or Japanese Cycas, have also been identified as potential causes of Charcot’s disease. [Leemage via AFP]An abnormally high concentration of ALS cases had then been linked the consumption of the seed of a local plant, the Japanese cycad (Cycas revoluta), traditionally consumed in the form of flour by the indigenous Chamorro population of the island. Cases of the disease have dropped since cycad seeds were banned from local cuisine.
However, the “false morel” contains a toxin similar to those of cycads, gyromitrin, which is transformed in the body into monomethyl hydrazine, a genotoxic chemical compound, or a substance capable of causing a dangerous change in the genetic material.
Forbidden for sale, but still consumed
The toxicity of these “false morels” has long been known, and the mushroom is already banned for sale in many European countries. However, its level of toxins being extremely variable depending in particular on the climate, it is still consumed in northern Europe or in mountainous regions.
Thus, some patients from Savoy admit having been seriously inconvenienced after meals comprising gyromiters mixed with real morels. But the long-term neurotoxic effects were not known.
Focus on feeding the sick
This is a first exploratory article concerning this fungus. Further work will have to prove the direct cause and effect link with the toxin. But if the hypothesis is confirmed, it is a step forward in the fight against this deadly disease, because it could help eliminate certain dietary risk factors.
So far, the exact causes of Charcot’s disease remain unclear. In the vast majority of cases, the disease appears after a spontaneous mutation of a gene. Several environmental risk factors were regularly cited, such as tobacco, pesticides or heavy metals. But none of them have been selected to assert direct causation.
In addition, with the exception of the case of Guam, the environmental causes of Charcot disease onset had rarely been analyzed in detail. This discovery therefore shows the importance of focusing on diet as well as the various exogenous factors to which patients suffering from ALS could have been exposed, underline the authors in their conclusion.