Table 1.
Comparison of CRISPR TA drive types
| Drive type | Threshold a | Suppression threshold b | Promoter | Engineering difficulty |
|---|---|---|---|---|
| TARE ( e ; f ; g ) | Low | N/A | Any | Proven (Champer, Lee, et al., 2020; Oberhofer et al., 2019) |
| TADE ( e ) | Low | Low | G | Medium |
| TADDE ( e ) | Low | N/A | Any | Medium? |
| TADS ( e ) | Zero | Zero | Any | High? |
| 1‐locus 2‐drive TARE | High | N/A | Any | Low |
| 2‐locus TARE | Medium | N/A | Any | Low |
| 2‐locus TADE | Medium | Very High | G,GE | Medium |
| 2‐locus TADDE | Medium | N/A | Any | Medium? |
| TADE Underdominance | Medium | High c | GE, GES d | Low? |
| TAHRE | Medium | Very High | G, GE | High? |
Blue shading indicates drives with high thresholds (likely allowing “safe” use in a wide variety of scenarios), drives that can flexibly use many different types of promoters, and drives that are anticipated or demonstrated as easier to engineer. Red represents drives without introduction thresholds and that use restricted promoters and are difficult to engineer. Yellow represents intermediate levels of these attributes.
Abbreviations: G, germline‐only promoter; GE, promoter with germline and early embryo cutting (in the progeny of drive‐carrying females); GES, promoter that induces a high rate of somatic cleavage.
Thresholds (for both modification and suppression) assume a small drive fitness cost and provide an indirect measure for the degree of confinement.
These are for suppression variants of the drive. N/A indicates that a strong suppression form of the drive is not possible.
A TADE Underdominance suppression system could have a “medium” threshold if it had intermediate early embryo cutting.
A strong suppression drive cannot use a GES promoter.
Champer, Kim, et al., 2020
Champer, Lee, et al., 2020
Oberhofer et al., 2019