Methods, systems and processes of identifying genetic variation in highly similar genes
View Patent ↗Provided herein are novel methods, systems and processes for mapping sequence reads to a modified reference genome and determining the presence or absence of a genetic variation, or the likelihood thereof, in a gene of interest in a subject.
1. A computer-implemented method for determining a likelihood of a presence or absence of a genetic variation in a gene of interest for a subject where the subject's genome also contains at least one counterpart gene to the gene of interest such that the at least one counterpart gene is at least 80% identical to the gene of interest, comprising the steps of:
(a) providing a modified reference genome comprising (i) the gene of interest and (ii) one or more counterpart genes to the gene of interest that are substantially altered, wherein at least 30% of nucleotides of the one or more counterpart genes of the modified reference genome are substituted with different nucleotides such that sequence reads obtained from the gene of interest of the subject or the at least one counterpart gene of the subject map to the gene of interest of the modified reference genome instead of to the one or more counterpart genes of the reference genome;
(b) mapping sequence reads obtained from the subject to the modified reference genome, wherein (i) the sequence reads are obtained from a sample obtained from a diploid subject using a massively parallel sequencing method, and (ii) the sequence reads obtained from the gene of interest and the at least one counterpart gene of the subject map to the gene of interest of the modified reference genome and not to the one or more counterpart genes of the modified reference genome, thereby providing sequence reads mapped to the gene of interest of the modified reference genome; and
(c) determining the likelihood of a presence or absence of a genetic variation in the gene of interest of the subject according to the sequence reads mapped to the gene of interest of the modified reference genome.
2. The method of claim 1 , wherein the mapping comprises an expectation that at least 4 alleles of the gene of interest of the subject map to the gene of interest of the modified reference genome.
3. The method of claim 1 , wherein a ploidy of at least 4 is expected for the gene of interest of the subject.
4. The method of claim 1 , wherein the at least one counterpart gene of the subject is at least 90% identical to the gene of interest of the subject.
5. The method of claim 1 , wherein the at least one counterpart gene of the subject is at least 95% identical to the gene of interest of the subject.
6. The method of claim 1 , wherein the at least one counterpart gene of the subject is a pseudogene of the gene of interest of the subject.
7. The method of claim 1 , wherein the at least one counterpart gene of the subject is 1 to 5 counterpart genes.
8. The method of claim 7 , wherein the at least one counterpart gene of the subject is 1 counterpart gene.
9. The method of claim 7 , wherein the at least one counterpart gene of the subject is 2 to 5 counterpart genes.
10. The method of claim 1 , wherein each of the at least one counterpart genes of the subject comprise two alleles.
11. The method of claim 1 , wherein the gene of interest of the subject comprises two alleles.
12. The method of claim 1 , wherein at least 50% of nucleotides of the one or more counterpart genes of the modified reference genome are substituted with different nucleotides.
13. The method of claim 1 , wherein the nucleotides of the one or more counterpart genes of the modified reference genome are substituted with ambiguous nucleotide markers.
14. The method of claim 13 , wherein the ambiguous nucleotide markers comprise an N.
15. The method of claim 1 , wherein one or more nucleotides of the one or more counterpart genes of the modified reference genome are deleted.
16. The method of claim 1 , wherein one or more nucleotides are inserted into the one or more counterpart genes of the modified reference genome.
17. The method of claim 1 , wherein the sequence reads are obtained for an entire genome.
18. The method of claim 1 , wherein the sequence reads are obtained by a chromosome-specific method or a gene-specific method.
19. The method of claim 1 , wherein the sequence reads are obtained by a method comprising paired-end sequencing.
20. The method of claim 1 , wherein the sequence reads are 100-200 bp in length.
21. The method of claim 1 , wherein the sequence reads represent at least 20-fold coverage of the gene of interest of the subject.
22. The method of claim 1 , wherein the sequence reads represent at least 50-fold coverage of the gene of interest of the subject.
23. The method of claim 1 , wherein the gene of interest of the subject is selected from PMS2, HBA1, HBG1, HBB, SBSD, and VWF.
24. The method of claim 23 , wherein the gene of interest of the subject is PMS2 and the at least one counterpart gene of the subject is PMS2CL.
25. The method of claim 23 , wherein the gene of interest of the subject is HBA1 and the at least one counterpart gene of the subject is HBA2.
26. The method of claim 23 , wherein the gene of interest of the subject is HBG1 and the at least one counterpart gene of the subject is HBG2.
27. The method of claim 23 , wherein the gene of interest of the subject is HBB and the at least one counterpart gene of the subject is HBD.
28. The method of claim 23 , wherein the gene of interest of the subject is SBDS and the at least one counterpart gene of the subject is SBDSP1.
29. The method of claim 1 , wherein the gene of interest of the subject is selected from CYP2D6, CYP21A2, PKD1 and PRSS1.
30. The method of claim 1 , where the determining of (c) comprises determining the presence or absence of the genetic variation in the gene of interest of the subject.
31. The method of claim 30 , wherein the presence or absence of the genetic variation is determined by a method comprising LR-PCR and re-sequencing.
32. The method of claim 1 , wherein the absence of the genetic variation in both the gene of interest of the subject and the at least one counterpart gene of the subject is determined in (c).
33. The method of claim 1 , wherein the likelihood of the presence of the genetic variation in either or both of the gene of interest of the subject and the at least one counterpart gene of the subject is determined in (c).
34. The method of claim 1 , wherein a presence of the genetic variation in the gene of interest of the subject or the at least one counterpart gene of the subject is determined after (c).
35. The method of claim 34 , wherein the presence of the genetic variation in the gene of interest of the subject is determined after (c) by sequencing the gene of interest of the subject.