G→T Transversion

A G→T transversion is a specific type of DNA mutation in which a guanine (G) base is replaced by a thymine (T) base. It is one of several possible single-base substitutions, and certain environmental exposures and oxidative damage processes leave behind characteristic patterns enriched in this particular change. Researchers can sometimes infer the likely cause of a tumor's mutations by looking at how often G→T transversions appear relative to other mutation types.

Origin

The term comes from classical genetics nomenclature, where "transversion" describes a substitution between a purine base (A or G) and a pyrimidine base (C or T), as distinguished from a "transition" between two purines or two pyrimidines. The concept dates to the 1950s–60s as DNA chemistry and mutation classification were formalized.

Significance in Asbestos Context

G→T transversions are a recognized signature of oxidative DNA damage, which is one of the mechanisms by which asbestos fibers are believed to injure cells. When asbestos fibers are retained in tissue, they generate reactive oxygen species (often through iron on the fiber surface) that damage guanine bases, and unrepaired damage can convert G to T during DNA replication. In mesothelioma and asbestos-related lung cancer research, an elevated proportion of G→T transversions in tumor sequencing is sometimes cited as molecular evidence consistent with an oxidative, fiber-driven mutational process, supporting the biological link between fiber exposure and the specific cancer in a patient.

Example Sentence

The molecular pathology report noted an excess of G→T transversions in the tumor's mutation profile, a finding the expert linked to oxidative damage from long-retained asbestos fibers.

Related Terms

Reactive Oxygen Species, Oxidative DNA Damage, Mutational Signature, 8-oxoguanine, BAP1, Somatic Mutation

Notes

• If your tumor has been sent for next-generation sequencing or whole-exome sequencing, ask whether a mutational signature analysis was performed and whether G→T transversions are over-represented.
• Preserve copies of any molecular pathology, genomic, or biomarker reports. These can become important scientific evidence linking your specific tumor to an asbestos-related mechanism.
• Ask your oncologist or pathologist whether the tumor's mutation pattern is consistent with oxidative damage versus other known causes (such as tobacco, which has its own characteristic signature).
• This kind of molecular evidence is most often discussed in mesothelioma and asbestos-related lung cancer cases; raise it with your legal team if sequencing was performed.