From Psychology Wiki

Community portal · Tasks to do · News · Help

Clinical · Educational · Ind&Org · Other fields · Professional · Transpersonal · World

Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Personality | Philosophy | Research Methods | Social | Statistics

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology

---

Pleiotropy occurs when a single gene influences multiple phenotypic traits. Consequently, a new mutation in the gene will have an effect on all traits simultaneously. This can become a problem when selection on one trait favours one specific mutant, while the selection at the other trait favours another mutant.

Contents 1 Etymology 2 Mechanism 3 Other examples 4 See also

[edit] Etymology

The term pleiotropy comes from the Greek pleio, meaning "many", and tropo, meaning "changes".

[edit] Mechanism

Pleiotropy describes the genetic effect of a single gene on multiple phenotypic traits. The underlying mechanism is that the gene codes for a product that is for example used by various cells, or has a signalling function on various targets.

The easiest way to explain the mechanism is to use an example. A classic example of pleiotropy is the human disease PKU (phenylketonuria). This disease causes mental retardation, and reduced hair and skin pigmentation. The cause is a mutation in a single gene that codes for an enzyme (phenylalanine hydroxylase) that converts the amino acid phenylalanine to tyrosine, another amino acid. The mutation results in a no or reduced conversion of phenylalanine to tyrosine, and phenylalanine concentrations increase to toxic levels, causing damage at several locations in the body.

[edit] Other examples

Antagonistic pleiotropy refers to a situation in which a single gene creates multiple competing effects, such that beneficial effects of a trait created by the gene are offset by 'losses' in other traits. One example is a theory of aging first developed by G. C. Williams in 1957. Williams suggested that one gene is responsible for increased fitness when young at the expense of fitness later in life (i.e. aging). Another example might be a gene in a bacterium which confers increased glucose utilization efficiency at the expense of other carbon sources (such as lactose).

[edit] See also

• Epistasis
• Metabolic network

edit The development of phenotype
Key concepts: Genotype-phenotype distinction | Norms of reaction | Gene-environment interaction | Heritability | Quantitative genetics
Genetic architecture: Dominance relationship | Epistasis | Polygenic inheritance | Pleiotropy | Plasticity | Canalisation | Fitness landscape
Non-genetic influences: Epigenetic inheritance | Epigenetics | Maternal effect | dual inheritance theory
Developmental architecture: Segmentation | Modularity
Evolution of genetic systems: Evolvability | Mutational robustness | Evolution of sex
Influential figures: C. H. Waddington | Richard Lewontin
Debates: Nature versus nurture
List of evolutionary biology topics

de:Pleiotropie

es:Pleiotropialv:Plejotropijapt:Pleiotropia

This page uses content from the English-language version of Wikipedia. The original article was at Pleiotropy. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.