CTCF^KO homozygous and CTCF^KO/CTCF^P30.6 transheterozygous zygotic mutants mostly reach adulthood, with some dying as pharate adults; the progeny of CTCF^KO homozygous mothers also mostly reach adulthood; CTCF^KO maternal-zygotic mutants progress through embryogenesis without detectable lethality but only survive until the pharate adult stage. CTCF^KO/CTCF^GE24185 transheterozygous adults progress through embryo-larva stages with relatively normal viability but only half progress from pupa to adulthood; the progeny of CTCF^KO/CTCF^GE24185 transheterozygous mothers also develop through embryo-larva stages with relatively normal viability but less than half progress from pupa to adulthood.

CTCF^KO zygotic and maternal-zygotic adults/pharate adults exhibit homeotic transformations in the abdominal segments, which include ectopic pigmented patches in A4, ectopic hairs in the A6 sternite, the formation of an A7 segment and protruding and rotated genitalia; the homeotic defects become more severe in maternal-zygotic mutants, with additional transformations (i..e the shape of A6 sternite is transformed toward that of A5, the shapes of A4 and A5 sternites are transformed toward that of A6, and ectopic bristles appear in a rudimentary A7 sternite. Maternal-only mutant adults (ie, progeny of homozygous mothers and wild-type fathers) are phenotypically normal except for ectopic pigmentation patches in A4 in about half of males.

CTCF^KO/CTCF^GE24185 zygotic-only and maternal-only mutants, as well as CTCF^KO/CTCF^P30.6 zygotic mutants, also exhibit homeotic transformations in the abdomen.