Recombination between the FRT sequences of the progenitor P-elements, resulting in deletion of the majority of FASN2 and the 5-prime non-coding exon of FASN1. The resulting chimeric P-element links the 5-prime region of FASN2 to most of the FASN1 genomic sequences. FASN2 expression is not detected and FASN1 transcript levels are severely reduced.

Lethal at the L1 larval stage. Lethality can be partially rescued by growing flies on a low carbohydrate diet supplemented with butter and egg yolk (as dietary lipid sources); addition of 10% sucrose to this diet results in total lethality at L1 stage.