Page - 83 - in Critical Issues in Science, Technology and Society Studies - Conference Proceedings of the 17th STS Conference Graz 2018

can be passed on to at most half of the offspring (Burt 2003). In laboratory experiments with gene drives, almost 100% of the offspring were converted to genetically modified organisms (GMOs) (Gantz et al. 2015). When organisms have a short generation time like insects, then already after a few months, a large part of the population could have a new property transmitted by the gene drive. In particular, very invasive gene drives may be able to impose properties on entire populations that would otherwise not spread. But gene drives not only affect the environment, the environment may affect gene drives as well. One of the main hurdles is the ability of organisms to change their genetic code and undergo mutational changes over time. So far, gene drives prove to be only partially successful in laboratory approaches (Lin and Potter 2016; Marshall et al. 2017). In addition, it is still unclear whether gene drives are manageable at all (Noble et al. 2018). Among the gene drive-mechanisms known so far, rather ‘passive’ techniques and more ‘active’ systems can be distinguished. Passive systems deliver certain genes to subsequent generations, because only offspring carrying a particular combination of genetic elements (e.g., a toxin and its antidote) survives. In active drive-systems, a bias of the sex ratio by (enzymatic) mechanisms or “copying” of genetic information between homologous chromosomes by Homing Endonuclease Genes (HEG) generates genomic modifications. The development of new gene drive variants is closely linked to the upswing that genome editing methods have taken by the recent use of the CRISPR/Cas “gene scissors”. Since its first description as a new molecular "gene scissors" in 2012, the CRISPR/Cas methodology has been widely used as an effective method of genome editing (Jinek et al. 2012; Doudna and Charpentier 2014). With CRISPR/Cas as homing-endonuclease the gene drive technology has become cheaper and easier to customize (Courtier-Orgogozo, Morizot, and Boëte 2017b). Progress is also evident in the semantics chosen by the participating researchers: Since the use of CRISPR/Cas, gene drives are called a 'mutagenic chain reaction' because of the self- propagating character and the high efficiency that could be achieved with this system (Gantz and Bier 2015). Gene drives based on CRISPR/Cas are comparably easy to handle, but the effectiveness of this system is still hampered by some problems, which however, could soon be solved in view of the rapid development in this area. For most applications gene drives are intended to spread in wild populations. Thereby they represent a shift of paradigms in the handling of GMOs. At least for the European Community, the current regulation of intended releases of GMOs assumes that for specific periods of time a certain amount of GMO will be released in a particular region1. With gene drives, a new type of genetic engineering appears whose aim requires an approach that exceeds these limits. A once-released gene drive represents an artificial intervention into ecosystems. Its ‘invasive’ character causes an inherent tendency to spread. Therefore, a loss of control is by far more probable than with common GMOs. Uncertainty concerning the potential consequences within ecosystems is growing with the spread of artificially induced changes. Technology assessment therefore refers to an increasing 'ignorance' associated with such powerful technologies. Options to reverse or restrict the spread and function of a technological intervention when things go wrong, as well as options to mitigate adverse effects are important for an effective risk 1 Cp. Annex III A and Annex III B of the Directive 2001/18/EC of the European Parliament and of the Council on the deliberate release into the environment of genetically modified organisms. 83