Provided herein is method for, among other things, estimating the number of sequence variations in a sample of DNA. In some embodiments, the method can be used to estimate the mutational load of a sample. In some embodiments, the method makes use of a set of primers that have 3′ ends that specifically hybridizes to a sequence that is repeated multiple times in the genome. Thermocycling a reaction mix containing the primers may produce a reaction product comprising at least 50 amplicons having a total length of at least 100 kb. This product can be sequenced to provide an estimate of the number of sequence variations in the sample, and thus the mutational load of the sample.