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NCI Dictionary of Genetics Terms


11 results found for: L



  • late or variable onset  listen  (layt … VAYR-ee-uh-bul …)
    The state in which a genetic trait is expressed later in life or is expressed at no fixed time in a life history.

  • LD 
    Where alleles (DNA markers) occur together more often than can be accounted for by chance because of their physical proximity on a chromosome. Also called linkage disequilibrium.

  • linkage  listen  (LING-kij)
    The tendency for genes or segments of DNA closely positioned along a chromosome to segregate together at meiosis, and therefore be inherited together.

  • linkage analysis  listen  (LING-kij uh-NA-lih-sis)
    A gene-hunting technique that traces patterns of disease in high-risk families. It attempts to locate a disease-causing gene by identifying genetic markers of known chromosomal location that are co-inherited with the trait of interest.

  • linkage disequilibrium  listen  (LING-kij dis-EE-kwih-LIH-bree-um)
    Where alleles (DNA markers) occur together more often than can be accounted for by chance because of their physical proximity on a chromosome. Also called LD.

  • locus  listen  (LOH-kus)
    The physical site or location of a specific gene on a chromosome.

  • locus heterogeneity  listen  (LOH-kus HEH-teh-roh-jeh-NEE-ih-tee)
    The situation in which mutations in genes at different chromosomal loci result in the same phenotype.

  • LOD score  listen  (… skor)
    A statistical estimate of whether two genetic loci are physically near enough to each other (or "linked") on a particular chromosome that they are likely to be inherited together. A LOD score of three or more is generally considered statistically significant evidence of linkage. Also called logarithm of the odd score.

  • logarithm of the odd score  listen  (LAW-guh-RIH-thum … skor)
    A statistical estimate of whether two genetic loci are physically near enough to each other (or "linked") on a particular chromosome that they are likely to be inherited together. A LOD score of three or more is generally considered statistically significant evidence of linkage. Also called LOD score.

  • LOH 
    If there is one normal and one abnormal allele at a particular locus, as might be seen in an inherited autosomal dominant cancer susceptibility disorder, loss of the normal allele produces a locus with no normal function. When the loss of heterozygosity involves the normal allele, it creates a cell that is more likely to show malignant growth if the altered gene is a tumor suppressor gene. Also called loss of heterozygosity.

  • loss of heterozygosity  listen  (… HEH-teh-roh-zy-GAH-sih-tee)
    If there is one normal and one abnormal allele at a particular locus, as might be seen in an inherited autosomal dominant cancer susceptibility disorder, loss of the normal allele produces a locus with no normal function. When the loss of heterozygosity involves the normal allele, it creates a cell that is more likely to show malignant growth if the altered gene is a tumor suppressor gene. Also called LOH.