METHODS FOR SIMULTANEOUS AMPLIFICATION OF TARGET LOCI
The invention provides methods for simultaneously amplifying multiple nucleic acid regions of interest in one reaction volume as well as methods for selecting a library of primers for use in such amplification methods. The invention also provides library of primers with desirable characteristics, such as minimal formation of amplified primer dimers or other non-target amplicons.
1 . A method for preparing a DNA fraction from a biological sample of a subject useful for analyzing genetic or epigenetic features associated with cancer, comprising:
(a) extracting cell-free DNA from the biological sample;
(b) preparing a DNA fraction by: introducing at least one adaptor containing a universal priming sequence into at least a subset of the extracted cell-free DNA or DNA derived therefrom to produce an adapted DNA population containing one or more target loci of interest, performing universal amplification on at least some of the adapted DNA population using the universal priming sequence to produce an amplified adapted DNA population, and selectively enriching for at least a subset of the amplified adapted DNA population or its derivative to produce enriched DNA; and
(c) performing massively parallel sequencing on the enriched DNA or its derivative to obtain sequence data from at least a portion of the one or more target loci of interest, and
(d) obtaining an identity derived from the sequence data of one or more genetic or epigenetic features associated with cancer.
2 . The method of claim 1 , wherein the biological sample is a blood, plasma, serum, or urine sample.
3 . The method of claim 1 , wherein the genetic or epigenetic features associated with cancer comprises single nucleotide polymorphism or variant, copy number variation, insertion, deletion, or nucleotide methylation.
4 . The method of claim 1 , wherein step (b) comprises selectively enriching for 1,000-500,000 loci.
5 . The method of claim 1 , wherein step (b) comprises selectively enriching for 10,000-200,000 loci.
6 . The method of claim 1 , wherein the selectively enriching comprises targeted multiplex amplification.
7 . The method of claim 1 , wherein the selectively enriching comprises capturing at least some of the amplified adapted DNA comprising one or more loci using hybrid capture probes.
8 . The method of claim 7 , wherein the selectively enriching further comprises amplifying the captured DNA using a second universal amplification.
9 . The method of claim 8 , wherein the second universal amplification introduces a sample-specific barcode.
10 . The method of claim 1 , wherein the adaptor further comprises a molecular barcode, wherein sequence reads derived from the same original cell-free DNA molecule are identified using the molecular barcode.
11 . The method of claim 1 , wherein the universal amplification introduces a sample-specific barcode, and wherein the enriched DNA of multiple samples are pooled together and sequenced in the same sequencing run.
12 . The method of claim 1 , wherein the cell-free DNA comprises cancer DNA, and wherein the method further comprises estimating the fraction of cancer DNA in the cell-free DNA based on the sequence reads.
13 . The method of claim 1 , wherein at least one of the one or more target loci of interest is selected from the group consisting of: a single nucleotide variation (SNV), a single nucleotide polymorphism (SNP), an indel, a methylation site, and a copy number variation (CNV).
14 . The method of claim 1 , wherein the one or more target loci of interest includes two target loci of interest, one of which contains a single nucleotide variation (SNV) and another of which contains a nucleotide methylation site.