Systems and methods to detect rare mutations and copy number variation
The present disclosure provides a system and method for the detection of rare mutations and copy number variations in cell free polynucleotides. Generally, the systems and methods comprise sample preparation, or the extraction and isolation of cell free polynucleotide sequences from a bodily fluid; subsequent sequencing of cell free polynucleotides by techniques known in the art; and application of bioinformatics tools to detect rare mutations and copy number variations as compared to a reference. The systems and methods also may contain a database or collection of different rare mutations or copy number variation profiles of different diseases, to be used as additional references in aiding detection of rare mutations, copy number variation profiling or general genetic profiling of a disease.
1. A method, comprising:
(a) providing at least one set of tagged parent polynucleotides by converting initial starting genetic material, which is cell-free nucleic acid, into the tagged parent polynucleotides, wherein converting comprises tagging by enzymatic ligation with n different molecular barcodes, wherein n is at least 2 and no more than 10,000*z, wherein z is a mean of an expected number of duplicate molecules in the plurality of polynucleotides having identical start and stop positions;
(b) amplifying the tagged parent polynucleotides in the set to produce a corresponding set of amplified progeny polynucleotides;
(c) sequencing at least a subset of the set of amplified progeny polynucleotides to produce set of sequencing reads;
(d) collapsing the set of sequencing reads to generate a set of consensus sequences, wherein a consensus sequence corresponds to a unique polynucleotide among the set of tagged parent polynucleotides; and
(e) analyzing the set of consensus sequences using one or more bioinformatics processes to detect methylation profiles, wherein the analyzing comprises determining a quantitative measure of polymorphic forms from among a plurality of consensus sequences, wherein the polymorphic forms comprise methylation, hypermethylation, and hydroxymethylation.
2. The method of claim 1 , wherein the initial starting genetic material is obtained from a sample of a subject.
3. The method of claim 2 , wherein the sample is selected from the group consisting of blood, plasma, serum, urine, saliva, mucosal excretions, sputum, stool, and tears.
4. The method of claim 2 , wherein the sample comprises between 1 nanogram (ng) and 100 ng of the cell-free nucleic acid.
5. The method of claim 1 , wherein the initial starting genetic material comprises 100 to 100,000 haploid human genome equivalents of cell-free nucleic acid.
6. The method of claim 1 , wherein the enzymatic ligation is performed using blunt-end ligation or sticky-end ligation.
7. The method of claim 1 , wherein n different molecular barcodes is no more than 1,000*z.
8. The method of claim 1 , wherein n different molecular barcodes is no more than 100*z.
9. The method of claim 1 , comprising enriching the amplified progeny polynucleotides prior to the sequencing in (c) for regions of interest.
10. The method of claim 9 , wherein the enriching comprises selectively enriching for regions of interest that comprise genomic sequences of genes, oncogenes, tumor suppressor genes, promoters, or regulatory sequence elements.
11. The method of claim 1 , further comprising mapping the set of sequencing reads to a reference sequence to generate mapped sequencing reads.
12. The method of claim 11 , further comprising, prior to (d), grouping a plurality of mapped sequencing reads into families using sequence information from the molecular barcodes, a start base position of a given mapped sequence read from among the plurality of mapped sequence reads at which the given sequence read is determined to start mapping to the reference sequence and a stop base position of the given mapped sequence read at which the given sequence read is determined to stop mapping to the reference sequence.
13. The method of claim 12 , wherein the collapsing in (d) comprises generating a consensus sequence from each family from among one or more of the families.
14. The method of claim 2 , wherein the subject has cancer.
15. The method of claim 1 , further comprising detecting cancer in a subject based on the methylation profile determined in (e).
16. The method of claim 13 , further comprising identifying one or more consensus sequences comprising a somatic genetic variant as compared to the reference sequence.
17. The method of claim 16 , wherein the somatic genetic variant comprises a single nucleotide variant (SNV), an insertion or deletion (indel), a copy number variation (CNV), or a gene fusion.
18. The method of claim 17 , further comprising detecting cancer in the subject when the presence of the one or more somatic genetic variants is detected.