The present disclosure relates to methods for detecting unique genetic signatures derived from markers such as, for example, mutations, somatic or germ-line, in nucleic acids obtained from biological samples. The sensitivity of the methods provides for detection of mutations associated with a disease, e.g., cancer mutations, or with inherited disease, e.g., an autosomal recessive disease, in a noninvasive manner at ultra-low proportions of sequences carrying mutations to sequences carrying normal, e.g., non-cancer sequences, or a reference sequence, e.g., a human reference genome.