Notched-winged females of this X-linked dominant mutation survive only as a heterozygote.
The closely linked recessive white-eye, facet-eye, and split-bristle mutant alleles exhibit the mutant phenotype in these heterozygotes.
This is explained by pseudodominance: the genes for these 3 loci resided on a deletion, together with theN gene.
Such individuals are partially hemizygous.