A 19.3 kb region of the bithorax complex (BX-C), roughly corresponding to the iab-6 cis-regulatory domain (Drosophila genome project release 5 coordinates 3R:12705250-12724572 ), is replaced with a 255 bp attP site. The previously identified IAB5 initiator fragment and the Fab-7 boundary element are left intact by the deletion, while the region presumed to be the Fab-6 boundary is removed.
Flies homozygous for Abd-Biab-5.6.CI have both their abdominal A5 and A6 segments transformed towards A4.
Males homozygous for Abd-Biab-5.6.CI display A4-like pigmentation pattern on both the fifth and sixth abdominal tergites. Also, the A6 sternite which is normally devoid of bristles displays numerous bristle like A4 or A5 sternite.
Abd-Biab-5.6.CI mutants are fertile.