NCI Dictionary of Genetics Terms

26 results found for: S

Sanger sequencing: (SANG-er SEE-kwen-sing); A low-throughput laboratory method used to determine the nucleotide sequence of a piece of DNA. Sanger sequencing uses polymerase chain reaction (PCR) to amplify the target DNA region and then sequences the PCR products.
screening: (SKREE-ning); Checking for disease in individuals who have no symptoms. Since screening may find diseases at an early stage, there may be a better chance of curing the disease. Screening may also include genetic testing to check for an individual's risk of developing an inherited disease.
SDR: An aunt, uncle, grandparent, grandchild, niece, nephew, or half-sibling of an individual. Also called second-degree relative.
sebaceoma: (seh-BAY-shee-OH-muh); A benign yellow or flesh-colored lesion originating from an oil gland in the skin. Sebaceomas are typically found on the face or neck. They may be associated with Muir-Torre syndrome, which is a hereditary syndrome associated with the development of several types of cancer. Also called sebaceous epithelioma.
sebaceous epithelioma: (seh-BAY-shus EH-pih-THEE-lee-OH-muh); A benign yellow or flesh-colored lesion originating from an oil gland in the skin. Sebaceous epitheliomas are typically found on the face or neck. They may be associated with Muir-Torre syndrome, which is a hereditary syndrome associated with the development of several types of cancer. Also called sebaceoma.
second-degree relative: (SEH-kund-deh-GREE REH-luh-tiv); An aunt, uncle, grandparent, grandchild, niece, nephew, or half-sibling of an individual. Also called SDR.
segregation analysis: (SEH-greh-GAY-shun uh-NA-lih-sis); The process of fitting formal genetic models to data on expressed disease characteristics (phenotype) in biological family members in order to determine the most likely mode of inheritance for the trait or disease under study.
sensitivity: (SEN-sih-TIH-vih-tee); The frequency with which a test shows a true positive result among individuals who actually have the disease or the genetic variant in question. A test with high sensitivity has a low false-negative rate, which means it does a good job of correctly identifying affected individuals or carriers of a genetic variant.
single nucleotide polymorphism: (SING-gul NOO-klee-oh-tide PAH-lee-MOR-fih-zum); A DNA sequence variation that occurs when a single nucleotide (adenine, thymine, cytosine, or guanine) is different from the reference sequence. Single nucleotide polymorphisms are usually present in at least 1% of the population and are the most common type of genetic variation among people. Single nucleotide polymorphisms may increase the risk of developing certain diseases, act as biomarkers to help predict the risk of developing certain diseases or how a person may respond to certain drugs, or be used to track the inheritance of disease-causing variants within families. Also called SNP.
single nucleotide variant: (SING-gul NOO-klee-oh-tide VAYR-ee-unt); A DNA sequence variation that occurs when a single nucleotide (adenine, thymine, cytosine, or guanine) in the genome sequence is altered. Single nucleotide variants may be rare or common in a population. Sometimes single nucleotide variants are referred to as single nucleotide polymorphisms if they are present in at least 1% of the population. Also called SNV.
sister chromatid exchange: (SIH-ster KROH-muh-tid ex-CHAYNJ); Mitotic crossover between homologous chromosomes.
skin tag: (skin tag); A small, benign skin growth that may have a stalk (peduncle). Skin tags most commonly appear on the neck, axillary, groin, and inframammary regions. Also called acrochordon.
SNP: (snip); A DNA sequence variation that occurs when a single nucleotide (adenine, thymine, cytosine, or guanine) is different from the reference sequence. SNPs are usually present in at least 1% of the population and are the most common type of genetic variation among people. SNPs may increase the risk of developing certain diseases, act as biomarkers to help predict the risk of developing certain diseases or how a person may respond to certain drugs, or be used to track the inheritance of disease-causing variants within families. Also called single nucleotide polymorphism.
SNV: A DNA sequence variation that occurs when a single nucleotide (adenine, thymine, cytosine, or guanine) in the genome sequence is altered. SNVs may be rare or common in a population. Sometimes SNVs are referred to as single nucleotide polymorphisms if they are present in at least 1% of the population. Also called single nucleotide variant.
somatic mutation: (soh-MA-tik myoo-TAY-shun); In the context of cancer genetics, somatic mutation refers to a mutation in DNA that occurs before or during tumor development. This type of mutation is not present within the germline (sperm and egg). Also called somatic variant.
somatic variant: (soh-MA-tik VAYR-ee-unt); In the context of cancer genetics, somatic variant refers to a variant in DNA that occurs before or during tumor development. This type of variant is not present within the germline (sperm and egg). Also called somatic mutation.
Southern blot: (SUH-thern blot); Electrophoresis-based technique used in genetic testing to detect large deletions in DNA that can be missed by PCR-based genetic testing methods.
specificity: (SPEH-sih-FIH-sih-tee); The frequency with which a test shows a true negative result among individuals who do not have the disease or the genetic variant in question. A test with high specificity has a low false-positive rate, which means it does a good job of correctly identifying unaffected individuals or noncarriers of a genetic variant.
splice-site mutation: (... myoo-TAY-shun); A genetic alteration in the DNA sequence that occurs at the boundary of an exon and an intron (splice site). This change can disrupt RNA splicing resulting in the loss of exons or the inclusion of introns and an altered protein-coding sequence. Also called splice-site variant.
splice-site variant: (... VAYR-ee-unt); A genetic alteration in the DNA sequence that occurs at the boundary of an exon and an intron (splice site). This change can disrupt RNA splicing resulting in the loss of exons or the inclusion of introns and an altered protein-coding sequence. Also called splice-site mutation.
sporadic cancer: (spuh-RA-dik KAN-ser); Cancer that occurs in people who do not have an inherited genetic variant that would increase their risk for that cancer. Sporadic cancer is sometimes used to differentiate cancers that occur in these people from cancers that occur in people who are known or likely to carry a high-risk variant that increases their risk for cancer. Sporadic cancer is also sometimes used to describe cancer that occurs in people who do not have a family history of that cancer or other associated cancers.
sumLOD score: (... skor); The summation of all positive pedigree LOD scores (statistical estimates of whether two genetic loci are physically near enough to each other on a particular chromosome that they are likely to be inherited together) at each point in the genome. Also called summary logarithm of the odds score.
summary logarithm of the odds score: (SUH-muh-ree LAW-guh-RIH-thum … skor); The summation of all positive pedigree LOD scores (statistical estimates of whether two genetic loci are physically near enough to each other on a particular chromosome that they are likely to be inherited together) at each point in the genome. Also called sumLOD score.
surveillance: (ser-VAY-lents); In medicine, the ongoing evaluation of an individual who has an increased risk of developing a disease or who has a disease that appears to be clinically stable or not progressing. Surveillance is also used to find early signs that a disease has come back. In public health, surveillance may also refer to the ongoing systematic collection and analysis of information about the incidence, prevalence, morbidity, survival, and mortality related to a disease or health-related event in a certain group of people.
susceptibility gene mutation: (suh-SEP-tih-BIH-lih-tee jeen myoo-TAY-shun); A genetic alteration that increases an individual’s susceptibility or predisposition to a certain disease or disorder. When such a variant (or mutation) is inherited, development of symptoms is more likely, but not certain. Also called deleterious mutation, disease-causing mutation, pathogenic variant, and predisposing mutation.
synchronous cancer: (SING-kruh-nus KAN-ser); A term used to describe a new or second primary cancer that develops at the same time as the first primary cancer, either in the same organ or in a different organ with the same molecular basis. Synchronous cancer is not considered metastatic relapse.