While many designs for gene drives and sex ratio distorters have been proposed, most systems that have been constructed in laboratories would fall into one of the three main categories below.
Homing
These systems are based on a process of 'homing' in which the gene drive element is copied from one chromosome to its homologous partner chromosome. They are designed so that this 'homing' process occurs in germline cells, that is cells that produce the gametes (sex cells). The result is that the modified gene drive carrying chromosomes are passed on to the next generation at an artificially high rate.
Toxin antidote
These systems are based on the gene drive elements that encode some form of 'toxin' and an 'antidote'. When drive carrying individuals reproduce sexually the effect of the 'toxin' is to render some or all zygotes (fertilised gametes) unviable, unless these zygotes carry the gene drive element containing the 'antidote'. Because the action of the toxin disrupts inheritance of wild type alleles, over time the gene drive increases in frequency in the population.
'X-shredder'
These systems are based on a process that skews sperm production in XY males towards the generation of Y chromosome bearing sperm, with fewer X bearing sperm produced. This results in a higher fraction of male offspring and fewer females, potentially crashing a population. The most basic forms of 'X-shredder' do not bias their own inheritance and so are not considered gene drives. More sophisticated versions, mainly still hypothetical, would promote their own inheritance in various ways.
Other
These systems do not fall into any of the groups above. For more information on the design, please refer to the literature cited for this particular project.