Researchers in the USA have created a new type of edible mushroom by using genome editing (CRISPR-Cas) technology to delay browning when they are cut and prolong shelf-life. To do this, they blocked the function of several genes or changed their structure, thereby delaying natural processes. According to information issued by Penn State University where the mushrooms were developed, no additional genes were inserted and 'only' several small sequences removed from their DNA. The US authorities have already exempted these mushrooms from regulation without carrying out a more detailed assessment. Consequently, they can be produced and marketed in the same way as conventional food.
What is the problem?
In April 2016, the responsible US authority (APHIS) simply accepted the declaration made by the producer that no additional DNA had been inserted into the mushrooms. There was no investigation requested to find out if the deletion of the native DNA sequences might cause unintended changes in the composition of the mushrooms. Further, no data were made available on unintended changes likely to occur in the genome of the mushrooms. Even now there are no scientific publications available on the intended and unintended changes in the genome and / or the composition of the mushrooms.
This case clearly shows that where there is no regulation, there is also no access to reliable data. Under these circumstances, belief in the safety of the food products relies solely on the integrity of the producers - we can only hope that they are not hiding relevant facts or have unwittingly made mistakes.
In the EU, representatives of industry and other stakeholders want to influence policy to allow such products to be marketed without any risk assessment or labelling. They say that organisms with DNA that has only been changed or deleted in short sequences should not be regarded as genetically engineered. Their basic argument is that these changes could also occur spontaneously. However, the example of the CRISPR mushrooms shows they are wrong: Using CRISPR Cas technology resulted in parallel changes in the genome of the mushrooms to block the gene function that naturally causes browning. Such a specific pattern of parallel changes in the genome would not occur spontaneously. However, with CRISPR-Cas technology, several parallel changes in the genes are typical and often unavoidable: the gene scissors cut at all the sites in the genome where the respective gene sequences are located. For example, specific genetic information is often located at several sites in the genome of crop plants.
The CRISPR mushrooms exemplify a further problem: Available publications show that with the application of gene scissors there are frequently unintended changes in the genome of plants and animals. In consequence, also the overall composition of the mushrooms can be changed. Nevertheless, no detailed data has ever been published in regard to the mushrooms.
The removal of DNA sequences and blocking of gene functions can lead to health risks in just the same way and to the same extent as the insertion of additional genes. But the consumers would not be provided with any information about the risks and would not have a choice if there is no approval process and no labelling.
As yet, the mushrooms are not being marketed. However, it appears that the producers saw a lucrative business opportunity right from the start since they filed a patent on plants engineered with CRISPR-Cas technology as early as 2014.
In the meantime, a patent has been filed for the mushrooms.
In addition, Penn State University has announced that it will voluntarily pass further data to the US authorities. However, the safety of genetically engineered organisms cannot simply be left to individual proponents. There is a need for clear rules and risk assessments consistent with defined scientific standards.