Dominance (genetics)

autosomal recessiverecessiveautosomal dominantdominantrecessive genedominant genedominanceautosomal recessive disorderincomplete dominancerecessive trait
Dominance, in genetics, is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome.wikipedia
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Genetics

geneticgeneticistgenetically
Dominance, in genetics, is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome.
Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the context of a population.

X-linked dominant inheritance

X-linked dominantX-linked dominanceX-linked  dominant
The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes (autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked, and these show a very different inheritance and presentation pattern to autosomal traits which depends on the sex of the individual (see Sex linkage).
X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

Sex linkage

X-linkedsex-linkedX-linked trait
The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes (autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked, and these show a very different inheritance and presentation pattern to autosomal traits which depends on the sex of the individual (see Sex linkage).
They are characteristically different from the autosomal forms of dominance and recessiveness as they are different depending on the sex of the individual.

Allele

allelesallelicmultiple alleles
Dominance, in genetics, is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome.
In many cases, genotypic interactions between the two alleles at a locus can be described as dominant or recessive, according to which of the two homozygous phenotypes the heterozygote most resembles.

Gregor Mendel

MendelGregor Johann MendelMendelian
The concept of dominance was introduced by Gregor Johann Mendel.
To explain this phenomenon, Mendel coined the terms "recessive" and "dominant" in reference to certain traits.

Epistasis

epistaticgene interactiongenetic interactions
Dominance differs from epistasis, the phenomenon of an allele of one gene masking the effect of alleles of a different gene.
In this sense, epistasis can be contrasted with genetic dominance, which is an interaction between alleles at the same gene locus.

Hybrid (biology)

hybridhybridshybridization
However, when these hybrid plants were crossed, the offspring plants showed the two original phenotypes, in a characteristic 3:1 ratio, the more common phenotype being that of the parental hybrid plants.
The cross between two different homozygous lines produces an F1 hybrid that is heterozygous; having two alleles, one contributed by each parent and typically one is dominant and the other recessive.

Mutation

mutationsgenetic mutationmutated
This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (de novo) or inherited.

Gene

genesnumber of genesgene sequence
Dominance, in genetics, is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome.
Mendel was also the first to demonstrate independent assortment, the distinction between dominant and recessive traits, the distinction between a heterozygote and homozygote, and the phenomenon of discontinuous inheritance.

Sex chromosome

sex chromosomesallosomesex chromosomal
The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes (autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked, and these show a very different inheritance and presentation pattern to autosomal traits which depends on the sex of the individual (see Sex linkage).
An allele is either said to be dominant or recessive.

Sickle cell trait

sickle-cell traitsickle cell
(The medical condition produced by the heterozygous genotype is called sickle-cell trait and is a milder condition distinguishable from sickle-cell anemia, thus the alleles show incomplete dominance with respect to anemia, see above).
Those who are heterozygous for the sickle cell allele produce both normal and abnormal hemoglobin (the two alleles are codominant with respect to the actual concentration of hemoglobin in the circulating cells).

Mendelian inheritance

Mendelian geneticsMendelianMendel's laws
Dominance is a key concept in Mendelian inheritance and classical genetics.
If the two alleles of an inherited pair differ (the heterozygous condition), then one determines the organism’s appearance and is called the dominant allele; the other has no noticeable effect on the organism’s appearance and is called the recessive allele.

Genetic disorder

genetic diseasegenetic disordersgenetic diseases
These rare recessives are the basis for many hereditary genetic disorders.
Some types of recessive gene disorders confer an advantage in certain environments when only one copy of the gene is present.

Heredity

hereditaryinheritedinheritance
This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (de novo) or inherited.

Quantitative genetics

polygenicquantitative geneticquantitative geneticist
In quantitative genetics, where phenotypes are measured and treated numerically, if a heterozygote's phenotype is exactly between (numerically) that of the two homozygotes, the phenotype is said to exhibit no dominance at all, i.e. dominance exists only when the heterozygote's phenotype measure lies closer to one homozygote than the other.
In diploid organisms, the average genotypic "value" (locus value) may be defined by the allele "effect" together with a dominance effect, and also by how genes interact with genes at other loci (epistasis).

ABO blood group system

ABOABO blood groupABO blood groups
The blood type of a human is determined by a gene that creates an A, B, AB or O blood type and is located in the long arm of chromosome nine.
Individuals with I A I A or I A i have type A blood, and individuals with I B I B or I B i have type B. I A I B people have both phenotypes, because A and B express a special dominance relationship: codominance, which means that type A and B parents can have an AB child.

Mirabilis jalapa

Marvel of Perufour o'clock flowerbelle de nuit
A similar type of incomplete dominance is found in the four o'clock plant wherein pink color is produced when true-bred parents of white and red flowers are crossed.
The phenomenon is known as incomplete dominance.

Genotype

genotypesgenotypicgenotypically
The genetic makeup of an organism, either at a single locus or over all its genes collectively, is called its genotype.
With a dominant allele, the offspring is guaranteed to inherit the trait in question irrespective of the second allele.

Sickle cell disease

sickle cell anemiasickle-cell diseasesickle-cell anemia
(The medical condition produced by the heterozygous genotype is called sickle-cell trait and is a milder condition distinguishable from sickle-cell anemia, thus the alleles show incomplete dominance with respect to anemia, see above).
Sickle cell conditions have an autosomal recessive pattern of inheritance from parents.

Pea

peasPisum sativumgreen peas
A classic example of dominance is the inheritance of seed shape in peas.
Mendel reasoned that each parent had a 'vote' in the appearance of the offspring, and the non-dominant, or recessive, trait appeared only when it was inherited from both parents.

Haploinsufficiency

haploinsufficienthaplosufficiencyhaplo-insufficient
On the other hand, many autosomal dominant conditions result in the presence of a diseased form of a critical protein or simply not enough expressivity of the critical protein.
Haploinsufficiency in genetics describes a model of dominant gene action in diploid organisms, in which a single copy of the standard (so-called wild-type) allele at a locus in heterozygous combination with a variant allele is insufficient to produce the standard phenotype.

Classical genetics

classicalclassical geneticist
Dominance is a key concept in Mendelian inheritance and classical genetics.

Hardy–Weinberg principle

Hardy-Weinberg equilibriumHardy-Weinberg principleHardy–Weinberg equilibrium
The frequency of the heterozygous state (which is the carrier state for a recessive trait) can be estimated using the Hardy–Weinberg formula:
Hardy's paper was focused on debunking the then-commonly held view that a dominant allele would automatically tend to increase in frequency; today, confusion between dominance and selection is less common.

Huntington's disease

HuntingtonHuntington diseaseHuntington’s disease
The disease is caused by an autosomal dominant mutation in either of an individual's two copies of a gene called Huntingtin.

P53

TP53p53 genep53 protein
Such dominant-negative mutations occur in the tumor suppressor gene p53.
As such, mutations in the DBD are recessive loss-of-function mutations.