The nub¹ chromosome has previously been shown to have an insertion of 412 insertion in the promoter of one of the nub isoforms. In addition, the chromosome contains a 1824bp deletion (Df(2L)nub¹) downstream of nub, in the intergenic region between nub and pdm2. Expression of both nub and pdm2 is affected in the 412{}nub¹ Df(2L)nub¹ chromosome. Analysis of newly generated CRISPR alleles that carry a similar deletion to Df(2L)nub¹ (without a 412 insertion in nub) have a similar phenotype to 412{}nub¹ Df(2L)nub¹ flies, suggesting that the primary cause of the nub¹ phenotype is due to the Df(2L)nub¹ deletion rather than the 412{}nub¹ insertion.

The nub¹ chromosome has previously been shown to have an insertion of a 412 element in the promoter of one of the nub isoforms. In addition, the chromosome contains a 1823bp deletion (and three base insertion - TGT) designated (Df(2L)nub¹) downstream of nub, in the intergenic region between nub and pdm2.