Standardizing the Definition of Gene Drive

The authors invite those interested in gene drive technologies to indicate your support for this standardization initiative by becoming a signatory, and to use these definitions as appropriate in your publications and communications.

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Gene drive has become a hot topic in the popular press and the scientific literature, yet little consensus vocabulary on the subject exists. As members of the gene drive community, we have developed a set of definitions to help stakeholders discuss the topic and communicate using a common understanding of terms. A standard consensus definition of gene drive and a glossary of terms, noted here, will be of great use to a field that has implications for both researchers and the general public. If we don’t clarify these terms, we risk hampering the field, confusing the public and thereby risk the potential loss of a technology that may help solve some of the world’s most intractable problems in public health, conservation and food security.

Loosely, gene drive refers to a phenomenon whereby a particular heritable element biases inheritance in its favor, resulting in the gene becoming more prevalent in the population over successive generations. Thus, the gene is being “driven” to progressively increase its frequency in the population. Biasing inheritance may involve, for example, more than the familiar Mendelian 50:50 inheritance chance, or reducing the fitness of alternative genotypes without directly distorting Mendelian inheritance. Highly efficient gene drives can bias inheritance so heavily in their favor that the heritable element can rapidly reach high frequency, close to doubling its frequency from one generation to the next. The speed of this process is inversely correlated with generation time (for example, mosquitos have a generation time of 2-4 weeks, rats have a generation time of 12 weeks, while whale species can have generation times of >50 years). However, in all cases, acquisition of the heritable element is expected to occur much faster than with more conventional types of genetic change driven by natural selection.

Without a common understanding of standard terms, policy discussions on gene drive can become difficult and confusing. Discussions of policy become critical as governments begin to regulate the technology and as multilateral treaty organizations begin to consider whether and how to use the technology.

Excerpt from the paper:

“The following definitions have been agreed upon by the signatories and are proposed for widespread use…

Gene drive: “Gene drive” is used both to describe a process or phenomenon (the biological activity of gene drive) and to describe an object (“a gene drive”). The term sometimes is also used to describe a management tool or intent for product development or regulatory purposes.

1. Process or Phenomenon: A gene drive is a phenomenon of biased inheritance in which the prevalence of a genetic element (natural or synthetic) or specific alternate form of a gene (allele) is increased, even in the presence of some fitness cost. This leads to the preferential increase of a specific genotype that may determine a specific phenotype from one generation to the next, and potentially spread throughout a population.

Less technical version: A gene drive is a process that promotes or favors the biased inheritance of certain genes from generation to generation

1. Material Object: A gene drive is comprised of one or more genetic elements that can cause the process of biased inheritance in its favor. The set of necessary elements may be referred to as a gene drive system or simply a “gene drive.”   Note that the presence of gene drive elements will not necessarily cause gene drive – many gene drive systems will cause the gene drive phenomenon only under specific circumstances, e.g. if they are present in the population above a certain threshold frequency, or if fitness costs are below a certain threshold. Note that gene drive, when defined as an object, need not always confer preferential transmission. Gene drives must ensure biased inheritance under at least some circumstances, but not necessarily all circumstances. For example, some gene drive systems confer preferential inheritance only when present in the population above a threshold frequency.

Less technical version: A gene drive is any genetic element able to bias its inheritance within a population.

• Intention: A gene drive may be intended as a management tool to achieve a particular goal. A gene drive may include additional “cargo” elements, in addition to the drive components, that are intended to introduce new trait(s) into an interbreeding population so as to effect a change in the characteristics of the population. A gene drive also may cause effects directly, for example by inserting into and disrupting a target gene. Thus,

Less technical version: A gene drive is a tool to effect certain changes in a population.”

More related to this:

Principles for gene drive research

Gene drives: The good, the bad, and the hype

Gene drives accelerate evolution – but we need brakes

Gene Drives: Experience with gene drive systems that may inform an environmental risk assessment

Gene Drives – Wundermittel? Biowaffe?