Medical Definition of Linkage analysis

  • Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Linkage analysis: Study aimed at establishing linkage between genes. Today linkage analysis serves as a way of gene-hunting and genetic testing.

Linkage is the tendency for genes and other genetic markers to be inherited together because of their location near one another on the same chromosome.

A gene is a functional physical unit of heredity that can be passed from parent to child. All genes in humans are pieces of DNA. Most genes contain information for making a specific protein.

The term "genetic marker" is broader than a gene. A genetic marker is simply a segment of DNA with an identifiable physical location on a chromosome whose inheritance can be followed. A genetic marker can have a function and thus be a gene. Or a marker can be a section of DNA with no known function.

Because DNA segments that lie near each other on a chromosome tend to be inherited together, markers are often used as tools for tracking the inheritance pattern of a gene that has not yet been identified but whose approximate location is known.

The statistical estimate of whether two loci are likely to lie near each other on a chromosome and are therefore likely to be inherited together is called a LOD score. A LOD score of 3 or more is generally taken to indicate that the two loci are linked and are close to one another.

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Last Editorial Review: 1/25/2017

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