Methods of determining tissues and/or cell types giving rise to cell-free DNA, and methods of identifying a disease or disorder using same
The present disclosure provides methods of determining one or more tissues and/or cell-types contributing to cell-free DNA (“cfDNA”) in a biological sample of a subject. In some embodiments, the present disclosure provides a method of identifying a disease or disorder in a subject as a function of one or more determined more tissues and/or cell-types contributing to cfDNA in a biological sample from the subject.
1. A method of classifying a test subject sample as containing tumor DNA, the method comprising:
(a) obtaining sequences of at least a portion of cfDNA molecules present in a test sample from the test subject, wherein the sequences have endpoints and the sequences are mappable to genomic locations;
(b) calculating a set of test sample values indicative of the frequency of cfDNA endpoints mapping to single base genomic locations in a defined genome region comprising a plurality of single base genomic locations, wherein the test sample values are calculated using a mathematical transformation of a count of cfDNA endpoints mapping to the single base genomic locations in the genomic region and representing the distribution of the number of cfDNA endpoints occurring at multiple single base locations in the genome region;
(c) determining a likelihood that the test sample contains tumor DNA by comparing the test sample values calculated from the frequency of cfDNA endpoints in step (b), with a plurality of reference values, wherein the reference values are calculated as in step (b), and the genome region used in the calculation are the same as the genome region in step (a), wherein the reference values are determined from cfDNA in a plurality of reference samples obtained from individuals known to not have cancer or known to have cancer; and
(d) classifying the sample as (i) containing tumor DNA or (ii) not containing tumor DNA using the likelihood determined in step (c), wherein the classification is dependent upon meeting a classification threshold.
2. The method of claim 1 , wherein the plurality of reference samples is obtained from individuals known to not have cancer and from individuals known to have cancer.
3. The method of claim 1 , wherein steps (b) and (c) are performed for a plurality of genome regions.
4. The method of claim 1 , wherein at least one genome region comprises a transcription factor binding site.
5. The method of claim 1 , wherein at least one genome region comprises a CTCF binding site.
6. The method of claim 1 , wherein the cfDNA sequenced comprises DNA derived from hematopoietic cells and non-hematopoietic cells, and wherein at least a portion of the non-hematopoietic cells are tumor cells.
7. The method of claim 1 , wherein test values and reference values are calculated for a plurality of genomic locations.
8. The method of claim 1 , wherein the cfDNA is sequenced on a massively parallel DNA sequencer.
9. The method of claim 1 , wherein the sample is a blood sample.
10. The method of claim 9 wherein the reference samples are blood samples.