These stocks carry chromosomal rearrangements that juxtapose euchromatin and heterochromatin and show variegated expression of the white gene, the brown gene or other genes.

In some of these stocks, variegated gene expression is suppressed by the presence of known Su(var) mutations. In other stocks, variegated expression has become suppressed from the accumulation of unknown modifiers. It is often necessary to cross variegating rearrangements into different genetic backgrounds to see robust variegated gene expression.