8-Oxoguanine
Definition
An oxidised form of guanine produced by reactive oxygen species attacking the C8 position of the guanine ring. 8-Oxoguanine mispairs with adenine instead of cytosine, introducing G-to-T transversion errors in PCR-amplified profiles if the lesion is not repaired before amplification.
- Cause
- Oxidative damage from reactive oxygen species
- Site
- C8 position of the guanine ring
- Mispairs with
- Adenine instead of cytosine
- Resulting error
- G-to-T transversion
Common questions
How does this lesion affect forensic STR profiling?+
If the lesion is not repaired before PCR, the polymerase can insert adenine opposite it instead of cytosine, introducing a sequence error into amplified copies. This becomes a bigger risk in degraded or low-template samples with more oxidative damage.
Is 8-oxoguanine damage the same thing as an abasic site?+
No. An abasic site has lost its base entirely, while 8-oxoguanine is a chemically altered version of guanine that is still present but mispairs incorrectly during replication.
Related terms
- Abasic Site
- A position in the DNA backbone where the nitrogenous base has been lost, leaving only the deoxyribose-phosphate scaffold. Also called an AP...
- Depurination
- Hydrolytic cleavage of the N-glycosidic bond between deoxyribose and a purine base (adenine or guanine), generating an abasic (apurinic) site. Abasic sites...
- Internal Positive Control (IPC)
- An exogenous DNA template of known sequence and concentration added to the PCR reaction alongside the forensic sample. If the IPC fails...
- Ministr (Reduced-Size) STR
- A short tandem repeat assay redesigned so that the amplicon spans a shorter distance from primer to primer, typically less than 200...
- PCR Inhibitor
- A co-extracted substance that interferes with Taq polymerase activity or primer annealing. Common inhibitors in forensic samples include haemoglobin (from blood on...