NCI Dictionary of Genetics Terms
12 results found for: H
- haploinsufficiency
- (HA-ploh-IN-suh-FIH-shen-see)
- The situation that occurs when one copy of a gene is inactivated or deleted and the remaining functional copy of the gene is not adequate to produce the needed gene product to preserve normal function.
- haplotype
- (HA-ploh-tipe)
- A set of closely linked genetic markers or DNA variations on a chromosome that tend to be inherited together.
- hemizygous
- (HEH-mee-ZY-gus)
- Describes an individual who has only one member of a chromosome pair or chromosome segment rather than the usual two. Hemizygosity is often used to describe X-linked genes in males who have only one X chromosome. This term is sometimes used in somatic cell genetics where cancer cell lines are often hemizygous for certain alleles or chromosomal regions.
- hereditary cancer syndrome
- (heh-REH-dih-tayr-ee KAN-ser SIN-drome)
- A type of inherited disorder in which there is a higher-than-normal risk of certain types of cancer. Hereditary cancer syndromes are caused by inherited genetic variants and may be associated with several clinical manifestations. Examples of hereditary cancer syndromes include Lynch syndrome and hereditary breast and ovarian cancer syndrome. Also called family cancer syndrome and inherited cancer syndrome.
- hereditary predisposition
- (heh-REH-dih-tayr-ee PREE-dih-spuh-ZIH-shun)
- An increased chance or likelihood of developing a particular disease based on the presence of one or more genetic variants and/or a family history suggestive of an increased risk of the disease. Having a hereditary predisposition does not mean an individual will develop the disease. Lifestyle and environmental factors can also affect an individual's risk of disease. Also called genetic predisposition, genetic susceptibility, and inherited predisposition.
- heritability
- (HAYR-ih-tuh-BIH-lih-tee)
- The proportion of variation in a population trait that can be attributed to inherited genetic factors. Heritability estimates range from 0 to 1 and are often expressed as a percentage. A number close to 1 may be indicative of a highly heritable trait within a population. It should not be used to estimate risk on an individual basis.
- heteroduplex analysis
- (HEH-teh-roh-DOO-plex uh-NA-lih-sis)
- A laboratory method used to detect sequence differences between normal DNA and the DNA to be tested. Heteroduplex analysis is commonly used to screen for point variants (mutations) in a gene but does not identify the exact location of the variant.
- heterogeneity logarithm of the odds score
- (HEH-teh-roh-jeh-NEE-ih-tee 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 heterogeneity logarithm of the odds score is calculated in the presence of locus heterogeneity (when the same phenotype can be caused by mutations in genes at different chromosomal loci). Also called HLOD score.
- heterozygous genotype
- (HEH-teh-roh-ZY-gus JEE-noh-tipe)
- The presence of two different alleles at a particular gene locus. A heterozygous genotype may include one normal allele and one mutated allele or two different mutated alleles (compound heterozygote).
- HLOD score
- (... 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. An HLOD score is calculated in the presence of locus heterogeneity (when the same phenotype can be caused by mutations in genes at different chromosomal loci). Also called heterogeneity logarithm of the odds score.
- homozygous genotype
- (HOH-moh-ZY-gus JEE-noh-tipe)
- The presence of two identical alleles at a particular gene locus. A homozygous genotype may include two normal alleles or two alleles that have the same variant.