Gef26^Δ12 and Gef26^Δ12/Df(2L)BSC5 escapers have rough eyes that are reduced in size, wing blades that are bent downwards and distorted male genitalia.

At stage 14, the posterior part of the ventral nerve cord lacks macrophages in Gef26^Δ12 mutants, whereas in wild-type embryos, the ventral nerve cord is completely surrounded by macrophages. In some mutant embryos, the resulting ventral gap persists until later stages, while in others the gap eventually disappears toward stage 15. Macrophages are found in an aberrant, dorsal position beneath the amnioserosa in mutant embryos after germ band retraction. Gef26^Δ12 macrophages form smaller protrusions than in wild-type macrophages and do not achieve the even distribution seen in stage 15 wild-type embryos, resulting in the posterior-ventral part of the mutant embryo containing fewer macrophages than wild type. Other aspects of the migration, such as the migration along the dorsal epidermis, are not affected.