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 determining genetic mutations from an individual, comprising:
determining whether a genetic mutation is present by analyzing a biological sample from the individual to determine a level of allelic imbalance for each of a plurality of chromosomes or chromosome segments known to exhibit cancer-associated mutations by:
amplifying at least 10 polymorphic loci relating to the cancer-associated mutations from each of the plurality of chromosomes or chromosome segments of circulating tumor DNA in the biological sample from the individual to obtain amplicons, wherein the amplifying comprises a first PCR to simultaneously amplify the at least 10 polymorphic loci by contacting the biological sample with at least 10 non-identical primers that simultaneously hybridize to the at least 10 polymorphic loci, followed by a second, nested PCR to simultaneously amplify the at least 10 polymorphic loci with at least 10-non-identical inner primers, wherein the polymorphic loci are single nucleotide variance loci,
generating nucleic acid sequence data for a set of polymorphic loci on each of the plurality of chromosomes or chromosome segments by performing high throughput sequencing of the amplicons, wherein more than 80% of the amplicons map to the targeted polymorphic loci,
using the nucleic acid sequence data to generate allelic data for the set of polymorphic loci on each of the plurality of chromosomes or chromosome segments, and
determining the level of allelic imbalance for each of the plurality of chromosomes or chromosome segments using the allelic data, wherein a detectable allelic imbalance is indicative of a genetic mutation.
2. The method according to claim 1 , wherein the nucleic acid sequence data for the set of polymorphic loci on each of the plurality of chromosomes or chromosome segments is corrected for allele amplification bias, ambient contamination, and genotype contamination.
3. The method according to claim 1 , wherein the nucleic acid sequence data for the set of polymorphic loci on each of the plurality of chromosomes or chromosome segments is corrected for allele amplification bias.
4. The method according to claim 1 , wherein the high throughput sequencing of the set of polymorphic loci on each of the plurality of chromosomes or chromosome segments is performed on a plurality of copies of a series of amplicons generated by a multiplex amplification reaction performed under limiting primer conditions, and wherein each amplicon of the series of amplicons spans at least one polymorphic loci of each set of polymorphic loci.
5. The method according to claim 1 , wherein the level of allelic imbalance is determined by modeling expected allelic frequencies for sets of hypothesis where cells have homolog deletions or amplifications, and identifying the maximum likelihood hypothesis.
6. The method according to claim 5 , wherein a likelihood of each hypothesis is determined at each polymorphic loci on each of the plurality of chromosomes or chromosome segments using a Bayesian classifier based on a beta binomial model of expected and observed allele frequencies.
7. The method according to claim 1 , wherein the high throughput sequencing of the plurality of single nucleotide variance loci is performed by sequencing a plurality of copies of a series of amplicons generated from a multiplex amplification reaction, and wherein each amplicon of the series of amplicons spans at least one single nucleotide variant loci of the plurality of single nucleotide variance loci.
8. The method according to claim 7 , wherein the multiplex amplification reaction of the single nucleotide variance loci are performed under limiting primer conditions.
9. The method according to claim 7 , wherein an efficiency and an error rate per cycle are determined for each amplification reaction of the multiplex amplification reaction of the single nucleotide variance loci, and the efficiency and the error rate are used to determine whether a single nucleotide variance at the set of single variance loci is present in the sample.
10. The method according to claim 1 , wherein determining whether a single nucleotide variant is present in the sample, comprises identifying a confidence value for each allele determination at each of the set of single nucleotide variance loci based at least in part on a depth of read for the loci.
11. The method according to claim 1 , wherein the plurality of single nucleotide variance sites comprises a plurality of the single nucleotide variance sites identified in the TCGA and COSMIC data sets.
12. The method according to claim 1 , wherein the method is performed with a depth of read for the plurality of single nucleotide variance loci of at least 100,000, and is capable of detecting a single nucleotide variant with a limit of quantification of 0.1% of the copies of that loci in the sample.
13. The method according to claim 1 , comprising generating nucleic acid sequence data for at least 10 single nucleotide variance loci known to be associated with cancer.
14. The method according to claim 1 , comprising generating nucleic acid sequence data for at least 50 single nucleotide variance loci known to be associated with cancer.
15. The method according to claim 1 , comprising generating nucleic acid sequence data for at least 100 single nucleotide variance loci known to be associated with cancer.
16. The method according to claim 1 , wherein the circulating tumor DNA is from breast cancer or ovarian cancer.
17. The method according to claim 1 , wherein the biological sample comprises blood, serum, or plasma.