660bp deletion within the sequences originating from the 1A region of the X chromosome that are present between the P{}y+sa and P{}y+sb insertions of the progenitor In(1)y2ps21sces chromosome. The deletion includes the 1A-RE insulator.
Mutants lack pigmentation in the abdomen and bristles. The sc mutant phenotype remains the same as in the original In(1)y2ps21sces.