UV dimers (red lines/links, center) occur due to covalent linkages between consecutive bases along the DNA. Following S-phase replication, only one sister clone will inherit the lesion-containing DNA duplex (gold). Left: Lesion retention for two cell cycles can give rise to multiallelic variation, in this case evidence for CC > CT mutations (1), as well as CC > TT (2). Right: Schematic representation of a biallelic mutation occurring in one cell cycle, followed by NER of the lesion-containing strand.
