From Big Medical Encyclopedia

PLEIOTROPIA (grech, pleion is more + than tropos turn) — influence of one gene on formation of various signs of an organism.

The item it is especially characteristic of terminal morfol, and fiziol, manifestations of action gene (see). E.g., the person has hereditary diseases etiologically caused by mutations of separate genes, differ, as a rule, in a wide range a wedge, manifestations, often in total forming specific syndromes. The same variety of manifestations on morfol, and fiziol, levels is characteristic also of genes at animals and plants.

It is known that action of genes at the level of primary products (RNA and polypeptides) differs in specificity: to each structural gene (to its coding part — exon) there corresponds the certain piece of RNA which is formed on a DNA matrix (RNA transcript), and the certain polypeptide synthesized as a result of broadcasting. Therefore, not plurality of primary manifestations of activity of genes, but interaction of products of genes secondary, tertiary etc. is P.'s reason at implementation of genetic information in a final morfofiziol. phenotype, i.e. The item reflects interrelation and interconditionality of development of structures and functions of an organism in the course of ontogenesis. Development of separately taken signs of an organism is defined not by one gene or their small number, and coordinate interaction practically of all genes of a genotype.

The range of pleyotropny action of a gene considerably depends on the place and time of its manifestation in ontogenesis. The more the number of types of cells and fabrics in which this gene is active the are more number of bodies and systems, in a structure and which functioning such activity can be tracked (so-called primary P.). The earlier in an embryogenesis this or that gene «works», the its action, even extends to bigger number of bodies and systems when primary effect of a gene was tightly local (so-called secondary P.). The Pleyotropny complex of signs is not always shown completely at all individuals of corresponding genotype (see). In many cases manifestation of the separate signs entering such complex can vary as on extent of manifestation (see. Penetrance of a gene ), and on degree of manifestation (see. Expressivity of a gene ). It is characteristic, e.g., of many hereditary diseases (see) and the majority of forms of multiple hereditary malformations at the person (see. Malformations ).

Bibliography: Gershenzon S. M. Fundamentals of modern genetics, Kiev, 1979; D at - and N and N. P N. General genetics, M., 1976; Lobashev M. E. Genetics, L., 1967; Goldschmidt R. Theoretische Gene-tik, B., 1961.

B. I. Ivanov.