with homozygosity extending ∼250 kbp from the rDNA array to the MET15 locus, and presumably the remaining ∼625 kbp to the telomere (Figure 1D). This LOH pattern is indicative of mitotic recombination events between homologous chromosomes. The fraction of mitotic recombination events originating within the rDNA array was significantly higher than expected based on the sequence distance represented by the rDNA array (based on a 95% confidence interval, binomial distribution), consistent with previous examinations of LOH at MET15 [11], [17]. Thus, MET15 LOH events are primarily serving as a read out for an age-associated increase in mitotic recombination that affects the rDNA array.
