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Dominant

A genetic trait is considered dominant if it is expressed in a person who has only one copy of that gene. (In genetic terms, a dominant trait is one that is phenotypically expressed in heterozygotes). A dominant trait is opposed to a recessive trait which is expressed only when two copies of the gene are present. (In genetic terms, a recessive trait is one that is phenotypically expressed only in homozygotes). Examples of dominant disorders include: {{}}Achondroplasia (a common form of dwarfism with short arms and legs), Familial hypercholesterolemia (high blood cholesterol leading to premature coronary artery disease), Huntington disease (a form of progressive dementia from which the folk singer Woody Guthrie suffered), Neurofibromatosis (NF1)(a neurologic disorder with an increased risk of malignant tumors), and Polycystic kidney disease (of adult onset). Most dominant trait are due to genes located on the autosomes (the non-sex chromosomes). An autosomal dominant trait typically affects males and females with equal likelihood and with similar severity. The gene responsible for it can be transmitted from generation to generation and each child born to someone with the gene has a 50:50 chance of receiving the gene and manifesting the disease.

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1. Ruling or controlling. 2. In genetics, denoting an allele possessed by one of the parents of a hybrid which is expressed in the latter to the exclusion of a contrasting allele (the recessive) from the other parent. [L. dominans, pres. p. of dominor, to rule, fr. dominus, lord, master, fr. domus, house]

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dom·i·nant -nənt adj

1) exerting forcefulness or having dominance in a social hierarchy

2) being the one of a pair of bodily structures that is the more effective or predominant in action <the \dominant eye>

3) of, relating to, or exerting genetic dominance

dom·i·nant·ly adv

dominant n

1) a dominant genetic character or factor

2) a dominant individual in a social hierarchy

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adj.

(in genetics) describing a gene (or its corresponding characteristic) whose effect is shown in the individual whether its allele is the same or different. If the allele is different it is described as recessive and its effect is masked. In genetic diseases showing autosomal dominant inheritance, the defective gene is dominant and will therefore be inherited by 50% of the offspring (of either sex) of a person with the disease. It will always be expressed in these offspring (since the normal allele inherited from the unaffected parent is recessive).

• dominant n.

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dom·i·nant (domґĭ-nənt) 1. exerting a ruling or controlling influence. 2. in genetics, capable of expression when carried by only one of a pair of homologous chromosomes. 3. in coronary artery anatomy, supplying the posterior diaphragmatic part of the interventricular septum and the diaphragmatic surface of the left ventricle; said of the right and left coronary arteries.

Medical dictionary. 2011.