Dictionary > X linkage

X linkage

noun, plural: X linkages
(genetics) A form of sex linkage involving particularly the X chromosome
The resulting phenotype or trait is due to the expression of a particular gene and when such gene occurs in the sex chromosome it is referred to as sex linkage. In mammals, including humans, the sex chromosomes are of two kinds: the X chromosome and the Y chromosome. Females typically possess two X chromosomes whereas males have one X chromosome (which is inherited from the female parent) and one Y chromosome (which is from the male parent). In this regard, sex linkage are of two forms, i.e. X linkage or Y linkage. X linkage is a sex linkage involving the X chromosome whereas Y linkage is a sex linkage involving the Y chromosome. Since there are more genes in the X chromosome than in the Y chromosomes there are more X-linked traits than Y-linked.
X linkage is the state of a genetic factor (gene) being borne on the X chromosome. The inheritance of these genes from the X chromosome is referred to as X-linked inheritance, and may either be recessive or dominant. For instance, a female offspring whose father has an X-linked dominant trait would manifest the trait as well whereas a male offspring would not since the X chromosome would be inherited from the mother lacking such trait. A mother carrying the X-linked dominant trait would have offspring with 50% chance of acquiring the trait. Examples of X-linked dominant inheritance are Alport’s syndrome, idiopathic hypoparathyroidism, Rett syndrome, and fragile X syndrome. When the X-linked trait is recessive, the mother would have a female offspring that does not manifest the trait but would be a carrier whereas a male offspring would show the trait as there is only one X chromosome and it comes from the mother. Examples of X-linked recessive inheritance are Hunter syndrome, haemophilia A and B, color blindness, and Wiskott-Aldrich syndrome.

  • Y linkage

See also:

  • X-linked inheritance

  • You will also like...

    Structural depiction of catalase, an enzyme
    Protein Activity and Cellular Metabolism

    Proteins have a crucial role in various biological activities. Get to know how proteins are able to perform as enzymes, ..

    human brain structure
    The Conscious & Unconscious Nervous System

    This tutorial elaborates on how the nervous system works, particularly at the tissue level of the brain. There are three..

    Lights' Effect on Growth
    Lights’ Effect on Growth

    This tutorial elaborates on the effect of light on plant growth. It describes how different plants require different amo..

    Cell Biology
    Cell Biology

    The cell is defined as the fundamental, functional unit of life. Some organisms are comprised of only one cell whereas o..

    Schematic diagram of DNA replication
    DNA Structure & DNA Replication

    DNA is a double helix structure comprised of nucleotides. A nucleotide, in turn, is made up of phosphate molecule, deoxy..

    Biological Viruses
    Biological Viruses

    Viruses possess both living and non-living characteristics. This unique feature distinguishes them from other organisms...