Medical Definition of Penetrant trait

  • 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.

Penetrant trait: A genetic trait (characteristic) that is present in the genome and manifests itself in the individual. By contrast, a nonpenetrant trait is one that, although present, does not manifest itself.

If, for example, 100 people have a particular genetic trait but only 80 of them express it, the penetrance of that trait is 80%. The trait is penetrant and expresses itself in 80% of people who have it.

Reviewed on 9/7/2018

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