In the w[m4] mutant, the eye color was variegated (red-white mosaic colored) where the white gene was expressed in some cells in the eyes and not in others. The mutation was described first by Hermann Muller in 1930. PEV is a heterochromatin-induced gene inactivation.
The w[m4] mutant displays variegated eye color, with white patches appearing in the eyes due to the expression of the white gene in some cells and not others. This mutation was first identified by Hermann Muller in 1930. PEV is a process where heterochromatin causes gene inactivation.