SYSTEMS AND METHODS FOR ESTIMATING CELL SOURCE FRACTIONS USING METHYLATION INFORMATION

Systems and methods are disclosed for determining a cell source fraction in a biological sample of a test subject. Nucleic acid fragments are obtained from a biological sample, comprising cell-free nucleic acid, of the test subject. A methylation state is obtained for each nucleic acid fragment in a first plurality of nucleic acid fragments. Each respective nucleic acid fragment is individually assigned a first score, thereby obtaining a first plurality of scores. Each respective score represents a likelihood that the corresponding nucleic acid fragment was obtained from a cell-free nucleic acid molecule associated with the first cell source. The first plurality of scores is transformed into a first plurality of counts, each count in the first plurality of counts being for a methylation site in a first predetermined set of methylation sites. A first cell source fraction for the test subject is estimated using the first plurality of counts.