NCI Dictionary of Genetics Terms

18 results found for: M

massively parallel sequencing: (MA-siv-lee PAYR-uh-lel SEE-kwen-sing); A high-throughput method used to determine a portion of the nucleotide sequence of an individual’s genome. This technique utilizes DNA sequencing technologies that are capable of processing multiple DNA sequences in parallel. Also called next-generation sequencing and NGS.
melanocytic macules associated with Peutz-Jeghers syndrome: (meh-LAN-oh-SIH-tik MA-kyools uh-SOH-see-ay-ted ... putz-JAY-gerz SIN-drome); Benign pigmented patches that are commonly found on the lips. They may also be found inside the mouth, on the fingers, or on the genitalia. Melanocytic macules are a characteristic feature of Peutz-Jeghers syndrome, which is a hereditary syndrome associated with several types of cancer.
metachronous cancer: (meh-TA-kruh-nus KAN-ser); A term used to describe a new or second primary cancer that develops months or years after a first primary cancer, either in the same organ or in a different organ.
MGPT: Genetic tests that use next-generation sequencing to test multiple genes simultaneously. Also called multigene panel test and multigene test.
microsatellite: (MY-kroh-SA-teh-lite); Repetitive segments of DNA scattered throughout the genome in noncoding regions between genes or within genes (introns). Microsatellites are often used as markers for linkage analysis because of their naturally occurring high variability in repeat number between individuals. These regions are inherently genetically unstable and susceptible to mutations.
microsatellite instability: (MY-kroh-SA-teh-lite in-stuh-BIH-lih-tee); A characteristic of cells that contain an abnormality in DNA mismatch repair. The presence of microsatellite instability can be a marker of a germline pathogenic variant in one of the DNA mismatch repair genes, as in the case of Lynch syndrome. Microsatellite instability can also occur sporadically. Also called MSI.
missense mutation: (MIS-sens myoo-TAY-shun); A genetic alteration in which a single base pair substitution alters the genetic code in a way that produces an amino acid that is different from the usual amino acid at that position. Some missense variants (or mutations) will alter the function of the protein. Also called missense variant.
missense variant: (MIS-sens VAYR-ee-unt); A genetic alteration in which a single base pair substitution alters the genetic code in a way that produces an amino acid that is different from the usual amino acid at that position. Some missense variants (or mutations) will alter the function of the protein. Also called missense mutation.
MLPA: A laboratory method commonly used for the detection of unusual copy number changes (insertions or deletions) of genomic sequences. Also called multiplex ligation-dependent probe amplification.
mode of inheritance: (… in-HAYR-ih-tunts); The manner in which a genetic trait, disorder, or risk of disorder is passed from one generation to the next. There are different modes of inheritance, and each mode of inheritance may result in a characteristic pattern of affected, unaffected, or at-risk individuals within a family. Examples are autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, and multifactorial inheritance.
mosaicism: (moh-ZAY-ih-SIH-zum); The occurrence of 2 or more cell lines with different genetic or chromosomal make-up, within a single individual or tissue.
MSI: A characteristic of cells that contain an abnormality in DNA mismatch repair. The presence of MSI can be a marker of a germline pathogenic variant in one of the DNA mismatch repair genes, as in the case of Lynch syndrome. MSI can also occur sporadically. Also called microsatellite instability.
mucosal neuroma: (myoo-KOH-sul noor-OH-muh); A benign tumor of nerve tissue commonly found on the tongue, lips, or in the gastrointestinal tract. Mucosal neuromas are a characteristic feature of multiple endocrine neoplasia type 2B (also known as MEN3), which is a hereditary syndrome associated with the development of medullary thyroid cancer.
multigene panel test: (MUL-tee-jeen PA-nil ...); Genetic tests that use next-generation sequencing to test multiple genes simultaneously. Also called MGPT and multigene test.
multigene test: (MUL-tee-jeen ...); Genetic tests that use next-generation sequencing to test multiple genes simultaneously. Also called MGPT and multigene panel test.
multiplex ligation-dependent probe amplification: (MUL-tee-plex ly-GAY-shun-deh-PEN-dent probe AM-plih-fih-KAY-shun); A laboratory method commonly used for the detection of unusual copy number changes (insertions or deletions) of genomic sequences. Also called MLPA.
mutation: (myoo-TAY-shun); A change in the usual DNA sequence at a particular gene locus. Although the term often has a negative connotation, mutations (including polymorphisms) can be harmful, beneficial, or neutral in their effect on cell function. The term variant is sometimes used as a synonym for the term mutation.
mutation analysis: (myoo-TAY-shun uh-NA-lih-sis); A germline genetic testing method targeted to detect a specific variant or mutation (such as a deleterious MSH2 variant previously identified in a family), panel of variants (such as the 3 BRCA pathogenic variants comprising the founder mutation panel for individuals of Ashkenazi Jewish ancestry) or type of variant (such as large deletions or insertions in the BRCA1 gene). This type of testing is distinct from complete gene sequencing or variant scanning. The latter are designed to detect most variants in the region being tested. Current usage also applies this term to any genetic test.