NCI Dictionary of Genetics Terms

10 results found for: I

incomplete penetrance: (in-kum-PLEET PEH-neh-trunts); Penetrance refers to the likelihood that a clinical condition will occur when a particular genotype is present. A condition is said to show incomplete penetrance when some individuals who carry the pathogenic variant express the associated trait while others do not. Also called reduced penetrance.
inconclusive result: (IN-kun-KLOO-siv reh-ZULT); A negative test result in an individual where a clearly deleterious mutation has not been found in any family members. The genetic risk status of such an individual must be interpreted in the context of his or her personal and family history. Also called indeterminate result and uninformative result.
indeterminate result: (IN-deh-TER-mih-nut reh-ZULT); A negative test result in an individual where a clearly deleterious mutation has not been found in any family members. The genetic risk status of such an individual must be interpreted in the context of his or her personal and family history. Also called inconclusive result and uninformative result.
informative: (in-FOR-muh-tiv); In genetic testing, a test result that reveals definitively the presence or absence of the germline genetic alteration associated with the hereditary disorder being assessed. In linkage analysis, the ability to distinguish between maternally inherited and paternally inherited DNA markers (polymorphisms) within or near a given gene of interest.
informed consent: (in-FORMD kun-SENT); A process of information exchange between a clinician and an individual or their legal proxy designed to facilitate autonomous, informed decision making. The informed consent process for genetic testing should include an explanation of the medical and psychosocial risks, benefits, limitations, and potential implications of genetic analysis, a discussion of privacy, confidentiality, the documentation and handling of genetic test results, as well as options for managing the hereditary disease risk. Also called consent process.
inherited cancer syndrome: (in-HAYR-ih-ted KAN-ser SIN-drome); A type of inherited disorder in which there is a higher-than-normal risk of certain types of cancer. Inherited cancer syndromes are caused by inherited genetic variants and may be associated with several clinical manifestations. Examples of inherited cancer syndromes include Lynch syndrome and hereditary breast and ovarian cancer syndrome. Also called family cancer syndrome and hereditary cancer syndrome.
inherited predisposition: (in-HAYR-ih-ted 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 an inherited 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 hereditary predisposition.
insertion: (in-SER-shun); A type of genetic change that involves the addition of a segment of DNA. It may be as small as a single base but can vary significantly in size.
intron: (IN-tron); The sequence of DNA in between exons that is initially copied into RNA, but is cut out of the final, mature messenger RNA transcript. Introns do not code for amino acids that make up the protein encoded by the gene.
inversion: (in-VER-zhun); A chromosomal defect in which a segment of the chromosome breaks off and reattaches in the reverse direction.