Diseased CRISPR pufferfish

Fish with a genetic disorder approved for consumption in Japan

‘Progress’ is going in the wrong direction: in Japan, diseased gene-edited CRISPR/Cas pufferfish could soon be marketed as food. The gene editing tool was used to knock out the function of genes controlling the appetite of the fish. Consequently, the fish suffer from a metabolic disorder. Their feed uptake is increased and they gain more weight compared to the natural species.

The leptin receptor gene in the fish was genetically altered. Disruption of this gene or a deficiency in the production of the leptin hormone is associated with weight gain and diabetes in mammals. It was also found that several fish species can suffer from other health issues affecting, for instance, embryonic development, kidneys, regulation of blood glucose and behaviour. So far, the fish with the artificial genetic defect have been used as disease models to explore complex metabolic disorders.

Currently, however, there are plans to rear the genetically engineered (GE) fish inheriting the gene defect of the leptin receptor in aquacultures and market them as food. Patents have already been filed for the fish. Several stakeholders are hoping to increase their profits from the increased weight gain in the fish. The Japanese authorities have already given the green light, and the fish will be sold through a specific website.

Authorities in Japan assume there are no risks to health or the environment as long as no additional genes are inserted into the genome of plants or animals. However, as the example of the GE puffer fish shows, science does not support this assumption: the blocked gene is involved in many metabolic functions and the process of New GE is complex, which means there can be many unintended side effects. For example, the composition of the fish tissue can be altered and the susceptibility of the fish to diseases and infections may be increased. In addition to the risks, further questions need to be asked about health and animal welfare.

This example shows that insufficient regulation of New GE can be the cause of seriously misguided developments. Applications of new genetic engineering techniques can result in plants and animals with extreme biological characteristics, which go beyond what can be achieved in conventional breeding. Without mandatory approval processes, more and more products from genetically engineered plants and animals may enter the market without having undergone risk assessment. This would also be questionable from an ethical perspective. It is paving the way for ‘progress’ to go in the wrong direction – with serious consequences for humans, animals and the environment.

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Further information: 
News article from Japan
Testbiotech-News on the GE pufferfish
Scientific publication about the role of the leptin hormone in fishes

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