Gene drive organisms are perhaps one of the most dangerous environmental applications of genetic engineering ever developed.

The differences between old and new genetic engineering techniques are based on the tools and mechanisms used in the process, as well as the possibility of targeting the sites of DNA changes and the type of the desired genetic modification.

‘Old genetic engineering techniques’ refer to procedures that introduce one or more genes of either the same or a foreign species into the DNA of an organism using bacterial plasmids or gene guns. The incorporation of inserted DNA in the genome thereby is left to chance.

‘New genetic engineering techniques” are based on methods such as CRISPR/-Cas, zinc finger nuclease or Talens. They too need to be introduced into the cell, before they can become active in its DNA. These methods have been dubbed “gene scissors” because they enable DNA sequences to be cut at a targeted site. The resulting cellular repair mechanisms are then used by biotechnologists to either knock out individual genes, to alter their function or to insert new gene sequences.

CRISPR/Cas is a so-called new genetic engineering technique discovered in 2012 by molecular biologists Emanuelle Charpentier and Jennifer Doudna. CRISPR is an acronym for Clustered Regularly Interspaced Short Palindromic Repeats. Bacteria use CRISPR sequences to remember and prevent attacks from viruses as part of their immune system. Doudna and Charpentier then turned this mechanism into a tool for biotechnology. CRISPR consists of two components: a DNA sequence search tool and an associated protein, called Cas (which is an abbreviation for CRISPR-associated). Cas can perform a double-strand break at a specific DNA target sequence. Repair mechanisms in the cell can mend this in three ways. Biotechnologists exploit these three repair mechanisms to either knock out existing gene sequences, insert only a single base pair, or insert an entirely new DNA sequence.

In 1865, the natural scientist Gregor Mendel discovered patterns of the natural inheritance of traits, which became known as Mendelian inheritance rules. These rules describe, among other things, that the probability of inheriting a genetic trait from two (homozygous) parents to their offspring is about 50%. Gene drives circumvent these Mendelian inheritance rules and establish “super-Mendelian” inheritance. This means that through a gene drive up to 100% of its offspring – over generations – inherit a certain genetic trait.

In addition, Gregor Mendel, together with Alfred Russel Wallace, coined the term natural selection. This core mechanism of evolution is also overridden by Gene Drives. In natural selection, primarily those traits that serve the survival of the species or the adaptation to a specific environment will prevail in populations and species. With gene drives, however, genetic traits that serve purely human purposes and offer no survival or adaptation advantage would now also be able to prevail in a population.

The term ‘mutagenic chain reaction’ was coined by gene drive inventors Valentino Gantz and Ethan Bier. When we say a gen drive triggers a chain reaction, we mean that the genetically modified genes of an organism equipped with a gene drive are unstoppably and irrevocably passed on to all its offspring – across generations – until all individuals of that population or species carry these genes.

In the case of genetically modified organisms (GMOs), a release describes the situation in which these organisms transfer from the contained system of a genetic engineering laboratory, where they were created, into an open, unregulated system like nature. Releases can happen intentionally – as in the context of a field trial for research purposes – or for targeted application purpose. But releases can also happen unintentionally and accidentally, for example when containment measures in research labs are inadequate.