Imprecise excision of the P{PTT-GB} element, removing the P{PTT-GB} insertion and resulting in a 560bp deletion in the first LamC exon. This lesion is located within both the LamC and ttv transcription units (since LamC is nested within an intron of ttv). However, only LamC function is affected, since the "EX296" chromosome complements ttv00681b and fails to complement LamCEP2199.