dMMR stands for **deficient mismatch repair**. It describes a tumor that has trouble fixing certain DNA copying errors. dMMR is most commonly discussed as a **cancer biomarker** (a test result that helps guide care). It is often evaluated in cancers such as colorectal and endometrial cancer, and sometimes in other tumor types.
Mismatch repair deficiency is a tumor feature in which a cell’s DNA “spell-check” system does not work properly. It can lead to a build-up of DNA errors as cells divide. In oncology, it is commonly used as a biomarker to help classify cancers and guide treatment choices. It is most often identified through laboratory testing on tumor tissue.
MSI-high is a tumor test result that describes a specific pattern of DNA change called high microsatellite instability. It is most commonly used in cancer pathology reports to help characterize a tumor’s biology. MSI-high can influence treatment planning, including whether immunotherapy might be considered.
MSI stands for **microsatellite instability**, a tumor biomarker measured in cancer tissue (and sometimes compared with normal tissue). It describes a pattern of DNA changes that can happen when a cell’s **DNA mismatch repair** system is not working well. MSI testing is commonly used in oncology to help guide **diagnosis, hereditary risk evaluation, and treatment selection**, especially for immunotherapy. It is most often discussed in cancers such as colorectal and endometrial cancer, but it can be relevant across multiple tumor types.
Microsatellite instability is a tumor DNA pattern that can appear when a cell’s DNA repair system is not working normally. It describes changes in short, repeated DNA sequences called microsatellites. It is commonly used in cancer testing to help classify tumors and guide treatment planning. It can also be used to raise or lower suspicion for an inherited cancer syndrome in some settings.
Rearrangement is a change in how DNA is organized inside a cell. In cancer care, Rearrangement usually refers to a structural DNA change that can create an abnormal “fusion” gene or alter gene control. It is most commonly discussed in molecular pathology reports and genetic testing results. Clinicians use Rearrangement findings to help classify cancers and, in some cases, guide treatment selection.
Deletion is a type of genetic change where a piece of DNA is missing. It can involve part of a gene, an entire gene, or a larger section of a chromosome. In oncology, Deletion is commonly discussed as a tumor (somatic) finding or, less often, an inherited (germline) change. It is usually identified through laboratory testing of blood, bone marrow, or tumor tissue.
Amplification means there are extra copies of a gene or a DNA region inside cancer cells. It is a type of genetic change that can make certain cancer-driving signals stronger. Amplification is most commonly discussed in tumor biomarker testing and molecular pathology reports. It can help clinicians understand prognosis and whether targeted therapies may be relevant.
Copy number variation is a change in how many copies of a DNA segment a person’s cells contain. It can involve extra copies (gains) or missing copies (losses) of genes or larger chromosome regions. In oncology, it is commonly used to help describe tumor biology and guide diagnostic classification. It is also used in genetics to evaluate inherited (germline) conditions.
Gene fusion is a genetic change where parts of two different genes become joined together. This joining can create a new “fusion” gene that may change how a cell behaves. Gene fusion is commonly discussed in cancer care because some fusions help drive tumor growth. It is also used in oncology testing to support diagnosis and guide treatment selection.