Specific genetic information is often present several times in the genome of plants. This also seems to be the case with edible mushrooms. The CRISPR/Cas gene scissors cut at all points where there is a corresponding gene sequences. As a result, these plants show a certain pattern of genetic modification that would often be difficult or impossible to achieve with conventional breeding, even if no additional genes are inserted. The resulting new gene combinations are also associated with new biological properties and new risks.
In the USA, edible mushrooms were created using new genetic engineering techniques, i.e. (CRISPR/Cas), to stop cut surfaces from turning brown; the mushrooms were meant to have a longer storage- and shelf-life. This was achieved by destroying the structure of a certain gene present in the mushroom in several copies. Such a pattern of genetic change would not appear spontaneously.
The responsible US authority, APHIS, approved the mushrooms in April 2016. This was because it was, in their view, sufficient that the developers said that no additional DNA had been inserted. No further investigations were required to check whether other substances in the mushrooms had changed. No data on unwanted changes in the genome were submitted. As a result, there is no scientific publication on how exactly the properties of these mushrooms were intentionally or unintentionally changed.
This example shows: New GE can override the natural mechanisms in the cells that maintain and restore the original gene functions. New GE can thus result in organisms with new gene combinations and extreme biological traits, which go beyond what can be achieved in conventional breeding. Without a legally prescribed authorisation procedure, there is insufficient data to assess the risks of consuming such genetically engineered organisms.