Position-effect variegation

Position-effect variegation is a variegation caused by the inactivation of a gene in some cells through its abnormal juxtaposition with heterochromatin.

The classical example is the Drosophila w[m4](speak white-mottled-4) translocation. In this mutation, an inversion on the X chromosome places the white gene next to pericentric heterochromatin. Normally, the white gene is expressed in every cell of the adult Drosophila eye resulting in a red eye phenotype. In the w[m4] mutant the eye color is variegated (red-white mosaic colored) where the white gene is expressed in some cells in the eyes and not in others. The mutation was described first by Hermann Muller in 1930.[1]

See also

References

  1. Hermann J. Muller (1930). "Types of visible variations induced by X-rays in Drosophila". Journal of Genetics. Springer India. 22 (3): 299–334. doi:10.1007/BF02984195.

Additional Selected References

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