3196bp deletion (plus insertion of a single G nucleotide). The deletion extends from 1377bp left of the P{GT1}btv^BG01771 insertion site rightwards into the intron between exons 11-12 of btv. The deletion thus deletes two exons from btv and introduces a frameshift. In addition, the lesion is predicted to remove 60 C-terminal amino acids from CG5674, replacing them through frameshifting with 24 unrelated amino acids before termination. The mutation was generated in heterozygotes containing both the P{GT1}btv^BG01771 and P{SUPor-P}KG02815 insertions, in the presence of P-element transposase (the mechanism of deletion cannot be verified, but the most likely event is simple imprecise excision of the P{GT1}btv^BG01771 element without flanking exchange).