Posted on 2024年 11月 6日
この記事の概要
A “dominant gene” is a gene that, in an allelic combination, is more likely to manifest a trait. When a dominant gene is present, the trait is more likely to be expressed, while a recessive gene is less likely to be expressed. For example, in the ABO blood group, type A and B genes are dominant to type O. A disease involving dominant genes is “Huntington's disease,” in which the risk of developing the disease is increased simply by inheriting the gene from one parent.
A “dominant gene” is the one in which a trait is more likely to be expressed in an allelic combination. When a dominant gene is present, the trait is more likely to be expressed and the recessive gene is less likely to be expressed.
Dominant traits are expressed at a relatively high frequency because a dominant gene can be inherited from only one parent and still manifest itself.
For example, in the ABO blood group, type A and B genes are dominant over type O genes. Therefore, a person with type A genes will appear as type A even though he or she has type O genes. Similarly, type B is dominant over type O, so type B traits are expressed.
The word “dominant” does not mean “superior,” but simply indicates that the trait is more likely to appear.
Huntington’s disease is one of the diseases in which the dominant gene is involved. Huntington’s disease is a neurodegenerative disease and is caused by a specific dominant gene. In the case of this disease, the likelihood of developing the disease is increased by simply inheriting the dominant morbid gene from one parent. In other words, because the disease gene is dominant, you are at risk of developing the disease if you carry just one of the genes.
The main symptoms of Huntington’s disease include “dancing sickness,” which makes it difficult to control movement, altered mental status, and cognitive decline. Thus, a family history of the disease should be taken into account, especially if there is a family history of the disease, since the risk of developing a dominant gene is passed from parent to child at a high rate.
Thus, “dominant genes” can be involved in either trait, regardless of whether it is a superior or inferior trait.
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