The present invention concerns a method for determining the identity of one or more single nucleotide polymorphisms (SNP) in a genome, comprising: (i) fragmenting a sample genome; (ii) contacting the fragments with an excess of a plurality of different oligonucleotide primers under conditions that permit a primer to form a duplex with a complementary region on a fragment, each primer having a predetermined sequence complementary to a sequence on the genome that is proximal to a putative SNP site, and the resulting duplexes being immobilised on a solid support; (iii) carrying out the sequencing reaction(s) and detecting the incorporation of bases onto the oligonucleotide primers to extend the primers to at least the SNP site; and(iv) comparing the resulting sequences to those of the reference one or more SNPs.
