Imprecise excision of the progenitor insertion, removing the entire P{lacW} element and resulting in a deletion extending upstream relative to Gγ1. The Gγ1 coding region is intact. By PCR, sequence from -981 to -1213 relative to the Gγ1 transcription start site does not amplify, but sequence from -2.4kb to -3.3kb does. The deletion thus removes the Gγ1 promoter/transcription start site as well as the upstream gene MrgBP. It is not known whether CG13751 and/or ana2 are affected.