A method of evaluating a sequence variation in a sample is provided. In some embodiments, the method may involve: amplifying a nucleic acid product from an initial sample; fragmenting an amount of the nucleic acid product to produce fragments; attaching an adaptor to each end of the fragments to produce adaptor-tagged fragments; sampling no more than 10% of the tagged fragments and amplifying them; sequencing at least some of the copies of the fragments to produce a plurality of sequence reads; grouping sequence reads for copies of fragments that have the same fragmentation breakpoints; deriving a consensus sequence for each of the read groups; and aligning the consensus sequences with a reference sequence.
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