TABLE 1.

Frameshift mutation probability

	Repeats in coding DNAa	Repeats in essential coding DNAa	Mutation rateb		Mutation probability, generation 160c
Repeat					Wild type	MMR−	Wild type	MMR−
≥10 A/T	143	22	4.7 × 10−8	3.1 × 10−4	0.00033	0.89
≥10 G/C	0	0	7.0 × 10−8	7.5 × 10−4	0.0	0.0
7 A/T	2998	561d	3.8 × 10−9	1.6 × 10−6	0.00068	0.25
7 G/C	81	18	1.9 × 10−8	7.6 × 10−6	0.00011	0.043

^aNumber of repeats in haploids (http://www.yeastgenome.org).

^bRates of frameshifts (mutations per generation) within indicated repeats in wild-type and MMR null strains, taken or estimated from Tran et al. (1997) and Harfe and Jinks-Robertson (2000). Note that rates at specific loci may vary, depending on factors such as chromosomal location and sequence context (Harfe and Jinks-Robertson 2000; Hawk et al. 2005). The probability of incurring mutations in a given set of sequences within a given number of generations was calculated assuming a Poisson distribution, as one minus the probability of incurring no mutations, which was calculated as p(x = 0) = e^{−(μ)(no. of loci) (no. of generations)}, where μ is mutations per locus per generation.

^cProbability of incurring frameshift mutations within essential genes containing the indicated type of repeat.

^dCalculated on the basis of the percentage of genes in the genome that are essential (18.7%).