Patent ID: 7285384

Claim:
A method of genotyping comprising: a) providing an array composition comprising: i) a substrate with a surface comprising discrete sites; and ii) a population of microspheres comprising at least a first and a second subpopulation, wherein the microspheres of said first subpopulation comprise at least first and second different target nucleic acid molecules from a first individual and the microspheres of said second subpopulation comprise at least first and second different target nucleic acid molecules from a second individual, wherein said at least first and second different target nucleic aicd molecules are covalently attached to each of said microspheres with first and second attachment moieties, respectively; wherein said microspheres are randomly distributed on said surface; b) contacting said array composition with a first set of extension probes that hybridize with at least said first target nucleic acid molecules adjacent to a first detection position to from an extension complex; c) contacting said extension complex with a composition comprising: i) at least a frist nucleotide; ii) polymerase; wherein said polymerase extends a first extension probe with said first nucleotide when said first nucleotide is complementary to said first detection position; and d) detecting the presence of said first nucleotide, whereby said genotype is determined.