page_title: Pleiotropy
hierarchical_section_title: Pleiotropy
caption_attribution_description: English: A very simple genotype-phenotype map that only shows additive pleiotropy effects. G1, G2, and G3 are different genes that contribute to phenotypes P1, P2, and P3. For all intents and purposes, G1 contributes a red color to the phenotype of an organism, G2 contributes a blue color to the phenotype of an organism, and G3 contributes a yellow color to the phenotype of an organism. Please note that these are not real genes, and any similarity to existing genes is purely coincidental. Interpretation of this simple map shows that G1 is the only gene that contributes to the P1 phenotype; thus, this phenotype is red. G1, G2, and G3 contribute to P2; thus, this phenotype is brown. G2 and G3 contribute to P3; thus, this phenotype is green.
context_page_description: Pleiotropy occurs when one gene influences two or more seemingly unrelated phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene. Mutation in a pleiotropic gene may have an effect on several traits simultaneously, due to the gene coding for a product used by a myriad of cells or different targets that have the same signaling function.
  Pleiotropy can arise from several distinct but potentially overlapping mechanisms, such as gene pleiotropy, developmental pleiotropy, and selectional pleiotropy. Gene pleiotropy occurs when a gene product interacts with multiple other proteins or catalyzes multiple reactions. Developmental pleiotropy occurs when mutations have multiple effects on the resulting phenotype. Selectional pleiotropy occurs when the resulting phenotype has many effects on fitness.
  An example of pleiotropy is phenylketonuria, an inherited disorder that affects the level of phenylalanine in the human body. Phenylalanine is an amino acid that can be obtained from food. Phenylketonuria causes this amino acid to increase in amount in the body, which can be very dangerous.
context_section_description: Pleiotropy (from Greek πλείων pleion, "more", and τρόπος tropos, "way") occurs when one gene influences two or more seemingly unrelated phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene. Mutation in a pleiotropic gene may have an effect on several traits simultaneously, due to the gene coding for a product used by a myriad of cells or different targets that have the same signaling function.
  Pleiotropy can arise from several distinct but potentially overlapping mechanisms, such as gene pleiotropy, developmental pleiotropy, and selectional pleiotropy. Gene pleiotropy occurs when a gene product interacts with multiple other proteins or catalyzes multiple reactions. Developmental pleiotropy occurs when mutations have multiple effects on the resulting phenotype. Selectional pleiotropy occurs when the resulting phenotype has many effects on fitness (depending on factors such as age and gender).
  An example of pleiotropy is phenylketonuria, an inherited disorder that affects the level of phenylalanine in the human body. Phenylalanine is an amino acid that can be obtained from food. Phenylketonuria causes this amino acid to increase in amount in the body, which can be very dangerous. The disease is caused by a defect in a single gene on chromosome 12 that codes for enzyme phenylalanine hydroxylase, that affects multiple systems, such as the nervous and integumentary system. Pleiotropy not only affects humans, but also animals, such as chickens and laboratory house mice, where the mice have the "mini-muscle" allele.
  Pleiotropic gene action can limit the rate of multivariate evolution when natural selection, sexual selection or artificial selection on one trait favors one allele, while selection on other traits favors a different allele. Some gene evolution is harmful to an organism. Genetic correlations and responses to selection most often exemplify pleiotropy.
caption: Simple genotype-phenotype map that only shows additive pleiotropy effects. G1, G2, and G3 are different genes that contribute to phenotypes P1, P2, and P3.
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "150", "Image YResolution": "150", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CC 2015 (Macintosh)", "Image DateTime": "2016:04:10 18:44:26", "Image ExifOffset": "172", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "310", "Thumbnail JPEGInterchangeFormatLength": "7207", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "1000", "EXIF ExifImageLength": "1000"}