Patent ID: 7501253

Claim:
A method of determining the length of a polynucleotide target, comprising: (a) hybridizing said polynucleotide target to an array of first probes having different, determined lengths to form duplexes between said polynucleotide target and said first probes; (b) hybridizing a second probe having a determined length to said duplexes, wherein said second probe displaces said polynucleotide target from said duplex if the length of said polynucleotide target is greater than the length of said first probe; (c) hybridizing a third probe having a determined length to said duplexes, wherein said third probe displaces said polynucleotide target from said duplex if the length of said polynucleotide target is less than the length of said first probe; (d) determining the length of said polynucleotide target by identifying in which of said duplexes said polynucleotide target was not displaced.