Position-effect variegation

（重定向自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.

单词	Position effect variegation
释义	Position effect variegation 英语百科 Position-effect variegation （重定向自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.
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