Variation in 3DPCR long-range Taq polymerase background mutation rate across the PCR block. (A) White spots correspond to PCR-positive samples for TP53 DNA. Those samples indicated by an asterisk were cloned and sequenced. (B) Mutation matrices for A6-, B3- and C2-derived sequences; transitions were invariably of the type N->T,A; the number of bases sequenced is given by n. (C) 5′ Dinucleotide context for the G->A and C->T transitions, with the expected values shown as horizontal bars. (D) A collection of the most highly mutated sequences. To compact the data, only variable sites are shown, their positions being identified above. Nucleotide positions should be read from top to bottom. To the right are the numbers of mutations per clone (mut) and the minimum number of recombination events (rec) to explain the complexity. Zones of recombination are highlighted in grey shading when possible.