| CPC C12Q 1/6886 (2013.01) [C12Q 1/6806 (2013.01); C12Q 1/6855 (2013.01); C12Q 2525/101 (2013.01); C12Q 2525/155 (2013.01); C12Q 2525/191 (2013.01); C12Q 2531/113 (2013.01); C12Q 2535/122 (2013.01); C12Q 2563/179 (2013.01)] | 15 Claims |

|
1. A method for detecting at least one mutation in a double-stranded circulating tumor DNA (ctDNA) molecule present in a sample obtained from a patient comprising
(a) ligating a plurality of Y-shaped adapters to both ends of the double-stranded ctDNA molecule to form a double-stranded adapter-ctDNA complex, each Y-shaped adapter comprising a first oligonucleotide strand and a second oligonucleotide strand;
(b) amplifying both strands of the adapter-ctDNA complex to produce first amplicons and second amplicons, wherein the first amplicons are derived from the first oligonucleotide strand, and the second amplicons are derived from the second oligonucleotide strand;
(c) sequencing the first and second amplicons; and
(d) detecting at least one mutation in the double-stranded ctDNA molecule, when a mutation detected in the first amplicons is consistent with a mutation detected in the second amplicons,
wherein the first oligonucleotide strand:
(i) comprises a first proximal region and a first distal region, wherein the first proximal region comprises a first unique molecular identifier sequence and a first spacer sequence having the sequence 5′ TGACT 3′ (SEQ ID NO: 49), wherein the first spacer sequence is located 3′ to the first unique molecular identifier sequence and wherein the “T” nucleotide located at the 3′ end of the first spacer sequence (SEQ ID NO: 49) contains a phosphorothioate bond; and
(ii) does not comprise a degenerate or semi-degenerate sequence,
wherein the second oligonucleotide strand
(i) comprises a second proximal region and a second distal region, wherein the second proximal region comprises a second unique molecular identifier sequence and a second spacer sequence having the sequence 5′ GTCA 3′ (SEQ ID NO: 50), wherein the spacer sequence is located 5′ to the second unique molecular identifier; and
(ii) does not comprise a degenerate or semi-degenerate sequence,
wherein the first proximal region of the first oligonucleotide strand hybridizes with the second proximal region of the second oligonucleotide strand,
wherein the first distal region of the first oligonucleotide strand does not hybridize with the second distal region of the second oligonucleotide strand,
wherein the second oligonucleotide strand comprises a nucleic acid sequence selected from the group consisting of:
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
and
wherein the Y-shaped adapters ligate to cell free DNA (cfDNA) at a concentration of as low as 5 ng.
|