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Like many other medical conditions, obesity is the result of an interplay between environmental and genetic factors. [2] [3] Studies have identified variants in several genes that may contribute to weight gain and body fat distribution, although only in a few cases are genes the primary cause of obesity.
The extreme endpoint of this distribution are the so-called 'monogenic' obesities where most of the impact on body weight can be tied to a mutation in a single gene that runs in a single family. The classic example of such a genetic effect is the presence of mutations in the leptin gene. [29]
Heredity of phenotypic traits: a father and son with prominent ears and crowns. DNA structure. Bases are in the centre, surrounded by phosphate–sugar chains in a double helix. In humans, eye color is an example of an inherited characteristic: an individual might inherit the "brown-eye trait" from one of the parents. [1]
Medical genetics is the application of genetics to medical care. It overlaps human genetics, for example, research on the causes and inheritance of genetic disorders would be considered within both human genetics and medical genetics, while the diagnosis, management, and counseling of individuals with genetic disorders would be considered part ...
Genetic effects are broadly divided into two categories: additive and non-additive. Additive genetic effects occur where expression of more than one gene contributes to phenotype (or where alleles of a heterozygous gene both contribute), and the phenotypic expression of these gene(s) can be said to be the sum of these contributions.
These genetic errors can affect the mind as well as the body and can result in schizophrenia, [14] [15] autism, [11] bi-polar disorder, [16] and cognitive [17] disabilities. Further information on mutations and cell division errors: Cystic fibrosis § Cause , Genetic origins of Down syndrome , Causes of autism , Chromosome abnormality , and ...
Ronald Fisher in 1913. Genetic variance is a concept outlined by the English biologist and statistician Ronald Fisher in his fundamental theorem of natural selection.In his 1930 book The Genetical Theory of Natural Selection, Fisher postulates that the rate of change of biological fitness can be calculated by the genetic variance of the fitness itself. [1]
In evolutionary biology, an evolutionary tradeoff is a situation in which evolution cannot advance one part of a biological system without distressing another part of it. In this context, tradeoffs refer to the process through which a trait increases in fitness at the expense of decreased fitness in another trait.