Microsatellite (2024)

FAQs

What does microsatellite data tell us? ›

​Microsatellite

These DNA sequences are typically non-coding. The number of repeated segments within a microsatellite sequence often varies among people, which makes them useful as polymorphic markers for studying inheritance patterns in families or for creating a DNA fingerprint from crime scene samples.

Microsatellites are useful genetic markers due to their multi-allelic nature. Scoring them is usually perfomed by typing the major alleles seen in electrophoretic gels. However, due to slippage of Taq polymerase during PCR, multiple amplification products are often present, complicating the accurate scoring of alleles.

Describes cancer cells that have a high number of mutations (changes) within microsatellites. For example, microsatellite testing that shows mutations in 30% or more microsatellites is called microsatellite instability-high. Microsatellites are short, repeated sequences of DNA.

If a cell's DNA is unstable, particles called microsatellites are produced. Colorectal cancer tumors are often referred to as having an “MSI status,” meaning they are described as either MSI or MSS. They cannot be both. An MSS (microsatellite stability) result indicates that the DNA in the cells are considered stable.

We've known since at least 2010 that early-stage cancers that had MSI had a significantly lower chance of recurrence. So that's been good news for a while for people with early-stage cancers. Before immunotherapy, MSI used to be very bad news for patients with advanced cancers.

Some limitations to the applicability of microsatellites include the following: (1) they are most effective when species-specific, and although they are often conserved within genera and even families, they may lose variability and thus effectiveness; (2) the mutation model remains unclear (infinite alleles vs stepwise ...

Microsatellites are widely used for DNA profiling, also known as "genetic fingerprinting", of crime stains (in forensics) and of tissues (in transplant patients). They are also widely used in kinship analysis (most commonly in paternity testing).

Molecular markers: tool for genetic analysis

Microsatellite markers in the STMS format can be completely described as information in databases and can serve as common reference points that will allow the incorporation of any type of physical mapping data into the evolving map.

Disadvantages of microsatellite markers

➢ In some situation, these markers give bias information since there are relatively few loci to work with.

Errors in DNA replication, recombination and mismatch repair cause microsatellite instability leading either to repeat tract expansion or contraction.

What is the difference between high and low microsatellite instability? ›

Three levels of MSI can be identified: high-level MSI (MSI-H), generally defined as MSI in more than 30% of the standard markers; low-level MSI (MSI-L), when changes are exhibited in less than 30% of the markers, and microsatellite stable (MSS) in the absence of microsatellite alterations.

Colorectal tumors that arise in patients with Lynch syndrome often have mutations in KRAS. Most cases of CRC associated with MSI are not inherited (familial), but arise through sporadic methylation-induced silencing of MLH1.

The pan-cancer presence of microsatellite instability (MSI)–positive tumors demonstrates its clinical utility as an agnostic biomarker for identifying immunotherapy-eligible patients.

Microsatellites (SSR--simple sequence repeats, STR--short tandem repeats, SSLP--simple sequence length polymorphism, VNTR--variable number of tandem repeats) are the class of repetitive DNA sequences present in all living organisms.

Microsatellites are widely used for DNA profiling, also known as "genetic fingerprinting", of crime stains (in forensics) and of tissues (in transplant patients). They are also widely used in kinship analysis (most commonly in paternity testing).

MSI screening has long been recognized as important in the care of patients with colorectal cancer (CRC) or endometrial cancer (EC). High-frequency MSI (MSI-H) is also recognized as a potential marker for germline mutations in certain DNA mismatch repair (MMR) genes associated with Lynch syndrome.

Microsatellite markers (also known as simple sequence repeats, SSRs) are a widely used marker system to estimate genetic diversity in population genetic studies and are often implicitly assumed to reflect the genome-wide diversity of a taxon [3].