BamBam: parallel comparative analysis of high-throughput sequencing data
The present invention relates to methods for evaluating and/or predicting the outcome of a clinical condition, such as cancer, metastasis, AIDS, autism, Alzheimer's, and/or Parkinson's disorder. The methods can also be used to monitor and track changes in a patient's DNA and/or RNA during and following a clinical treatment regime. The methods may also be used to evaluate protein and/or metabolite levels that correlate with such clinical conditions. The methods are also of use to ascertain the probability outcome for a patient's particular prognosis.
1. A computer implemented method of analyzing differences in sequences of a person, the method comprising:
accessing, by a computer, a first file of tumor reads from a tumor tissue of the person, wherein the tumor reads cover a set of sequence positions;
accessing, by the computer, a second file of normal reads from a normal tissue of the person, wherein the normal reads cover at least some of the set of sequences positions;
identifying, by the computer, at least one common sequence position from the set of sequence positions;
reading into RAM, by the computer, a set of tumor reads from the first file that overlap the at least one common sequence position;
reading into the RAM, by the computer, a set of normal reads from the second file that overlap the at least one common sequence position;
finding, by the computer, a tumor genotype and a germline genotype from the set of tumor reads and the set of normal reads, respectively, at the at least one common sequence position;
identifying, by the computer, at least one sequence difference at the at least one common sequence position based on at least one of the tumor genotype and the germline genotype; and
store, by the computer, the at least one sequence difference in a third file.
2. The method of claim 1 , wherein the normal reads represent a matched normal tissue relative to the tumor tissue.
3. The method of claim 1 , further comprising moving to a next common sequence position in the set of sequence positions and repeating an analysis of the tumor reads and the normal reads at the next common sequence position.
4. The method of claim 1 , further comprising keeping the first file and the second file in sync while reading the first file and the second file at the at least one common sequence position.
5. The method of claim 1 , wherein at least one of the first file and the second file stores reads according to a standardized BAM or SAM format.
6. The method of claim 1 , wherein at least one of the first and the second file stores RNA or DNA reads.
7. The method of claim 1 , further comprising generating a tumor pileup from the set of tumor reads and a normal pileup from the set of normal reads.
8. The method of claim 7 , wherein finding the tumor genotype and the germline genotype further comprises selecting the tumor genotype and the germline genotype based on the tumor pileup and the normal pileup respectively.
9. The method of claim 1 , wherein the least one sequence difference includes at least one of the following types of differences: a single nucleotide polymorphism (SNP), an insertion, a deletion, an inversion, a transposition, a repeat, a mutation, and a structural rearrangement.
10. The method of claim 1 , further comprising filtering the at least one sequence difference as a false positive.
11. The method of claim 10 , wherein filtering the at least one sequence difference is based on allele positions supporting the at least one sequence difference.
12. The method of claim 10 , wherein filtering the at least one sequence difference is based on reads from the set of tumor reads or the set of normal reads.
13. The method of claim 12 , wherein filtering the at least one sequence difference is based on a strand distribution of reads in supporting the at least one sequence difference.
14. The method of claim 13 , wherein filtering the at least one sequence difference includes detecting a skewing of the strand distribution relative to a random distribution.
15. The method of claim 1 , wherein identifying the at least one sequence difference includes determining that the at least one sequence difference has a score that exceeds a threshold value.
16. The method of claim 15 , wherein the score of the at least one sequence difference includes at least one of the following types of scores: a mapping quality score, a confidence score of at least one of the tumor genotype and the germline genotype, a count, an insert size, and an alignment score.
17. The method of claim 15 , wherein the threshold value comprises a user-defined threshold value.
18. The method of claim 1 , further comprising using a window to identify the at least one common sequence position.
19. The method of claim 1 , wherein identifying the at least one sequence difference comprises calculating a probability of at least one of the tumor genotype and the germline genotype as a function of a multinomial, wherein the multinomial is based on at least one of the set of tumor reads and the set of normal reads.