Abstract: The invention provides methods, systems, and computer readable medium for detecting ploidy of chromosome segments or entire chromosomes, for detecting single nucleotide variants and for detecting both ploidy of chromosome segments and single nucleotide variants. In some aspects, the invention provides methods, systems, and computer readable medium for detecting cancer or a chromosomal abnormality in a gestating fetus.

Abstract: Systems and method for determining variants can receive mapped reads, and call variants. In embodiments, flow space information for the reads can be aligned to a flow space representation of a corresponding portion of the reference. Reads spanning a position with a potential variant can be grouped and a score can be calculated for the variant. Based on the scores, a list of probable variants can be provided. In various embodiments, low frequency variants can be identified where multiple potential variants are present at a position.

Abstract: Systems and methods are used to identify an exon junction from a single read of a transcript. A transcript sample is interrogated and a read sequence is produced using a nucleic acid sequencer. A first exon sequence and a second exon sequence are obtained using the processor. The first exon sequence is mapped to a prefix of the read sequence using the processor. The second exon sequence is mapped to a suffix of the read sequence using the processor. A sum of a number of sequence elements of the first exon sequence that overlap the prefix of the read sequence, of a number of sequence elements of the second exon sequence that overlap the suffix of the read sequence, and of a constant is calculated using the processor. If the sum equals a length of the read sequence, a junction is identified in the read using the processor.