Nucleotide sequence exclusion enrichment by droplet sorting (NEEDLS)

An in vitro method for enriching for one or more target DNA molecules from a sample of mixed DNA molecules comprising the steps of:

• a) providing a liquid sample of mixed DNA molecules comprising non-target DNA molecules and one or more specific target DNA molecules and reagents for general amplification of DNA (401),
• b) formation of a multiple of liquid droplets each comprising mixed DNA molecules from said liquid sample (403),
• c) general amplification of said non-target and target DNA molecules in the multiple of droplets, wherein each droplet contains less than 0.5 of said one or more target DNA molecules on average (404),
• d) specific detection of said one or more target DNA molecules in droplets containing at least one of said target DNA molecules (405), and
• e) physically selecting droplets containing at least one of said target DNA molecules (406), wherein the frequency of the target DNA molecule compared to its frequency in the sample of mixed DNA molecules in step (a) is increased between 0.1×(number of droplets without target DNA)×(number of droplets with target DNA)−1 and 10×(number of droplets without target DNA)×(number of droplets with target DNA)−1.