Diseased CRISPR pufferfish

Fish with a genetic disorder approved for consumption in Japan

‘Progress’ is going in the wrong direction: In Japan diseased CRISPR/Cas gene edited 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 deficiency in the production of the leptin hormone is associated with weight gain and diabetes in mammals. It was also found in several fish species that the animals can suffer from other health issues affecting, for instance, embryonic development, kidneys, regulation of blood glucose and behaviour. Until now, 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 on the fish. Several stakeholders are hoping to push up their profits from the increased weight gain in the fish. The Japanese authorities have already given green light.

The authorities in Japan assume there are no risks for health or the environment as long as no additional genes get inserted into the genome of plants or animals. However, this assumption is not backed by science, as the example of the GE pufferfish shows: 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 may cause a severely misdirected development. In result, more and more products from genetically engineered plants and animals may enter the market without risk assessment and also being questionable from an ethical perspective. This would pave the way for ‘progress’ to take the wrong direction – with serious consequences for humans, animals and the environment.


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