Glossary
Terms, in plain language.
Definitions for words you'll meet across this site, with links to where they matter.
A
- Actionable alteration
- A molecular change for which there is evidence linking it to a treatment decision. 'Actionable' describes evidence, not a guarantee of benefit. Learn more
- Allele fraction (VAF)
- The proportion of sequencing reads at a position that carry a variant. It depends on tumour purity, copy number and whether the variant is clonal.
- Annotation
- Adding information to a detected variant — the gene and transcript affected, the predicted change to the protein, and links to databases. Learn more
C
- Circulating tumour DNA (ctDNA)
- Fragments of tumour DNA found in the bloodstream, which can be analysed from a blood sample. Learn more
- Clonal haematopoiesis
- Age-related genetic changes in blood-forming cells. These can appear in blood-based tests and be mistaken for tumour variants.
- Clonality
- Whether a variant is present in most tumour cells (clonal) or only a fraction of them (subclonal). Learn more
- Copy-number variation (CNV)
- A gain or loss of copies of a gene or larger segment of DNA.
D
- Digital twin
- In OnKommon Twin, a structured model of the available molecular and clinical information about a person's cancer, reviewed over time. It is not a complete copy of the patient. Learn more
- Drosophila melanogaster
- The common fruit fly, a long-established model organism in genetics and cancer biology. OnKommon AVATAR uses engineered flies in exploratory research. Learn more
E
- Evidence tier
- A graded label describing how strong and how relevant the evidence linking a finding to a clinical meaning is.
F
- FFPE
- Formalin-fixed, paraffin-embedded tissue — the standard way biopsy and surgical samples are preserved. Learn more
G
- Gene fusion
- Two genes joined together by a chromosomal rearrangement, sometimes producing an abnormal protein that drives cancer.
- Germline variant
- A variant present from birth in every cell, which may be inherited and may be passed on to children. Learn more
H
- HLA typing
- Identifying a person's human leukocyte antigen genes, which shape how the immune system recognises cells.
- Homologous recombination deficiency (HRD)
- A defect in a key DNA-repair pathway. It is relevant to some treatment decisions in certain cancers.
M
- Microsatellite instability (MSI)
- A pattern of DNA changes caused by faulty mismatch repair, relevant to some immunotherapy decisions.
- Molecular Tumour Board (MTB)
- A multidisciplinary meeting that reviews molecular findings and their clinical implications. KPCIRC convenes the Molecular Tumour Board that reviews OnKommon reports. Learn more
- Mutational signature
- A characteristic pattern of mutations left by a particular DNA-damaging process or repair defect. Learn more
P
- Pharmacogenomics (PGx)
- The study of inherited variants that affect how a person processes certain medicines. Learn more
R
- Research Use Only (RUO)
- A designation indicating that a product or output is not independently intended for diagnostic use or to direct patient care. Learn more
S
- Somatic variant
- A variant acquired by the tumour during a person's life, not inherited and not present in the rest of the body. Learn more
T
- Targeted panel
- A test that sequences a defined set of genes — for example the 523-gene Twin Liquid panel or the 335-gene Twin Tissue panel.
- Tumour mutational burden (TMB)
- The number of mutations in a tumour within the region tested. Values depend on the assay and are not always comparable.
- Tumour microenvironment (TME)
- The blood vessels, connective tissue and immune cells surrounding a tumour. Learn more
V
- Variant
- A difference in DNA sequence compared with a reference. Most variants are harmless; some contribute to disease. Learn more
- Variant of uncertain significance (VUS)
- A variant whose effect is not yet known. It should not by itself direct medical decisions. Learn more
W
- Whole-exome sequencing (WES)
- Sequencing of the protein-coding regions of the genome. Learn more