FLP-mediated recombination between the two progenitor insertions has resulted in a 13kb deletion of the genomic sequence between them.
The Df(3L)nkdΔUpE chromosome is homozygous semi-lethal, but Df(3L)nkdΔUpE/Df(3L)ED4782 is viable and fertile, indicating that the semi-lethality is due to a linked mutation(s) separable from the deficiency.