SEQUENCE ASSEMBLY USING OPTICAL MAPS
The invention generally relates to sequence assembly and particularly to ordering the alignment of contigs to reference maps. The invention provides systems and methods for assembling contigs by aligning those contigs to a reference map in descending order of placement confidence. Each placement decreases the number of possible placements for the remaining contigs, which otherwise would have been likely to match in numerous places. Contigs are thereby placed along the reference genome with confidence and thus can be assembled into a genome-scale sequence assembly.
1 . A method of assembling sequence contigs, the method comprising:
obtaining a plurality of sequence contigs;
determining a placement confidence score for each contig;
identifying a subset of the plurality of sequence contigs with a threshold placement confidence score;
aligning the contigs of the subset to a genomic map; and
aligning a remainder of the contigs to the genomic map.
2 . The method of claim 1 , further comprising aligning the contigs to the genomic map in order by placement confidence score.
3 . The method of claim 1 , wherein the placement confidence score comprises a length of a contig.
4 . The method of claim 1 , wherein the placement confidence score comprises a quality score.
5 . The method of claim 1 , wherein the subset is identified prior to any alignment of contig to map.
6 . The method of claim 1 , wherein the placement confidence score comprises a similarity metric.
7 . The method of claim 6 , wherein the subset comprises contigs that are most dissimilar to all of the other contigs in the plurality of sequence contigs.
8 . The method of claim 1 , wherein further comprising generating the genomic map by:
introducing nucleic acid from the sample to a charged substrate so that the nucleic acids become elongated and fixed on the substrate in a manner in which the nucleic acids remain accessible for enzymatic reactions;
digesting the nucleic acids enzymatically to produce one or more restriction digests; and
constructing a map from the restriction digests.
9 . The method of claim 8 , wherein the substrate is derivatized glass.
10 . The method of claim 1 , wherein the sample comprises human tissue or fluid.
11 . The method of claim 1 , further comprising generating an in silico optical map of at least some of the plurality of sequence contigs.
12 . The method of claim 6 , wherein the similarity metric comprises a measure of a number of cutting sites per length of nucleic acid molecule for a restriction enzyme.
13 . The method of claim 1 , further comprising:
using a computer system to perform the recited steps, wherein the computer system comprises a processor and a non transitory memory.