Imprecise excision of the progenitor insertion, resulting in a deletion that removes part of the Nc gene.
Less than 0.1% of homozygotes emerge as adult escapers (most homozygotes die as early pupae). The adult escapers have apparently normal morphology, except that their wings are opaque due to a failure of wing cells to undergo apoptosis.
Animals that are maternally and zygotically mutant for Nc are embryonic lethal, with almost complete absence of apoptosis.