HLA typing using selective amplification and sequencing
Presented herein are methods and compositions for determining haplotypes in a sample. The methods are useful for obtaining sequence information regarding, for example, HLA type and haplotype. Also presented herein are methods of determining haplotypes in a sample based on a plurality sequence reads.
1. A computer-implemented method of determining haplotypes in a sample comprising:
(a) receiving a plurality of paired sequencing reads of at least a portion of a first exon of an HLA gene and at least a portion of a second exon of the HLA gene, said plurality of paired sequencing reads comprising sequence information from at least two different haplotypes;
(b) partitioning each sequencing read into one of two different haplotypes by:
(i) randomly selecting a first and second paired sequencing read and designating said reads as haplotype 1 and haplotype 2, respectively;
(ii) assigning each remaining paired sequencing read in said plurality of paired sequencing reads to said haplotype 1 or said haplotype 2 based on sequence similarity to either haplotype 1 or haplotype 2;
(iii) computing a consensus sequence for haplotype 1 and a consensus sequence for haplotype 2 using the paired sequence reads assigned to each haplotype; and
(iv) designating said consensus sequences as haplotypes 1 and 2 and repeating steps (ii)-(iii) until said consensus sequences no longer change;
thereby determining haplotypes in said sample.
2. The method of claim 1 , wherein said partitioning comprises application of a k-means clustering algorithm.
3. The method of claim 1 , wherein said partitioning comprises application of an expectation-maximization clustering algorithm.
4. The method of claim 1 , further comprising repeating steps (f)-(i) at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or at least 20 times and selecting the consensus sequences that minimize the number of mismatches between the consensus sequence and the reads assigned to the haplotype assigned to the consensus sequence.
5. The method of claim 1 , wherein said assigning comprises computing the number of base mismatches between said sequencing read and the sequence of haplotypes 1 and 2.
6. The method of claim 1 , wherein said HLA gene is a Class I gene.
7. The method of claim 1 , wherein said HLA gene is a Class II gene.
8. The method of claim 1 , wherein said HLA gene is selected from the group consisting of: HLA-A, HLA-B and HLA-C.
9. The method of claim 1 , wherein said first region comprises at least 280, 290 or 300 nucleotides from the 5′ end of said exon pair.
10. The method of claim 1 , wherein said second region comprises at least 280, 290 or 300 nucleotides from the 3′ end of said exon pair.
11. The method of claim 1 , further comprising performing steps (b) and (c) a plurality of times.
12. The method of claim 1 , wherein said providing comprises an extension-ligation reaction.
13. The method of claim 1 , wherein said providing comprises a polymerase chain reaction.
14. The method of claim 1 , wherein said sequencing reads are carried out in a sequencing-by-synthesis (SBS) reaction.
15. A computer system for determining haplotypes in a sample, the system comprising:
a memory storing computer-readable instructions;
a processor configured to execute the computer-readable instructions to cause the computer system to:
receive a plurality of paired sequencing reads of at least a portion of a first exon of an HLA gene and at least a portion of a second exon of the HLA gene and a portion of an intron adjacent to the second exon, said plurality of paired sequencing reads comprising sequence information from at least two different haplotypes; and
partition each sequencing read into one of two different haplotypes by:
(i) randomly selecting a first and second paired sequencing read and designating said reads as haplotype 1 and haplotype 2, respectively;
(ii) assigning each remaining paired sequencing read in said plurality of paired sequencing reads to said haplotype 1 or said haplotype 2 based on sequence similarity to either haplotype 1 or haplotype 2;
(iii) computing a consensus sequence for haplotype 1 and a consensus sequence for haplotype 2 using the paired sequence reads assigned to each haplotype; and
(iv) designating said consensus sequences as haplotypes 1 and 2 and repeating steps (ii)-(iii) until said consensus sequences no longer change; thereby determining haplotypes in said sample.
16. A non-transitory computer readable medium for determining haplotypes in a sample, the computer-readable medium storing instructions that, when executed by at least one processor, causes a computer system to:
receive a plurality of paired sequencing reads of at least a portion of a first exon of an HLA gene and at least a portion of a second exon of the HLA gene and a portion of an intron adjacent to the second exon, said plurality of paired sequencing reads comprising sequence information from at least two different haplotypes; and
partition each sequencing read into one of two different haplotypes by:
(i) randomly selecting a first and second paired sequencing read and designating said reads as haplotype 1 and haplotype 2, respectively;
(ii) assigning each remaining paired sequencing read in said plurality of paired sequencing reads to said haplotype 1 or said haplotype 2 based on sequence similarity to either haplotype 1 or haplotype 2;
(iii) computing a consensus sequence for haplotype 1 and a consensus sequence for haplotype 2 using the paired sequence reads assigned to each haplotype; and
(iv) designating said consensus sequences as haplotypes 1 and 2 and repeating steps (ii)-(iii) until said consensus sequences no longer change; thereby determining haplotypes in said sample.