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Detection of target nucleic acids using hybridization

  • US 10,533,223 B2
  • Filed: 12/20/2016
  • Issued: 01/14/2020
  • Est. Priority Date: 08/06/2010
  • Status: Active Grant
First Claim
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1. An assay method for providing a statistical likelihood of a fetal copy number variation comprising:

  • providing a maternal plasma or serum sample comprising maternal and fetal cell free DNA;

    interrogating at least 48 non-polymorphic loci from a first target genomic region by hybridizing at least 48 first sets of at least two fixed sequence oligonucleotides to the maternal and fetal cell free DNA, wherein each of the at least two fixed sequence oligonucleotides in each first set comprises a region complementary to a locus in the first target genomic region, wherein one of the fixed sequence oligonucleotides of each first set comprises a capture region, a first label binding region, and two restriction sites;

    interrogating at least 48 non-polymorphic loci from a second target genomic region by hybridizing at least 48 second sets of at least two fixed sequence oligonucleotides to the maternal and fetal cell free DNA, wherein each of the at least two fixed sequence oligonucleotides in each second set comprises a region complementary to a locus in the second target genomic region, wherein one of the fixed sequence oligonucleotides of each second set comprises a capture region, a second label binding region, and two restriction sites, wherein the capture region in each second set is the same as a capture region in at least one first set;

    ligating the hybridized fixed sequence oligonucleotides;

    amplifying the ligated fixed sequence oligonucleotides to create amplicons;

    cleaving the amplicons at the restriction sites to create cleaved amplicons, wherein each cleaved amplicon comprises a capture region and the first or second label binding region;

    detecting the cleaved amplicons from the first and second target genomic regions via hybridization of the capture regions of the cleaved amplicons to an array comprising capture probes complementary to the capture regions, wherein the cleaved amplicons from the first and second target genomic regions hybridize competitively to the capture probes complementary to the capture regions;

    quantifying the capture regions of the cleaved amplicons to determine a relative frequency of the interrogated non-polymorphic loci from the first and second target genomic regions by detecting the first and second label binding regions;

    estimating the relative frequency of the first and second target genomic regions based on the determined relative frequency of the first and second label binding regions;

    interrogating at least 48 polymorphic loci from at least one target genomic region different from the first and second target genomic regions by hybridizing a third set of at least three fixed sequence oligonucleotides for each allele at each polymorphic locus, wherein one of the at least three fixed sequence oligonucleotides of each third set comprises a sequence complementary to one allele at a polymorphic locus, a capture region specific for each polymorphic locus, an allele-specific label binding region, and two restriction sites;

    ligating the hybridized fixed sequence oligonucleotides;

    amplifying the ligated fixed sequence oligonucleotides to create allele-specific amplicons;

    cleaving the allele-specific amplicons at the restriction sites to create cleaved allele-specific amplicons, wherein each cleaved allele-specific amplicon comprises a polymorphic locus-specific capture region and an allele-specific label binding region;

    detecting the cleaved allele-specific amplicons from the polymorphic loci via competitive hybridization of the polymorphic locus-specific capture regions of the cleaved allele-specific amplicons to capture probes on the array;

    quantifying the alleles of the polymorphic loci by detecting the allele-specific label binding regions for each allele on the cleaved allele-specific amplicons to determine the fraction of fetal DNA in the sample;

    determining the fraction of fetal DNA; and

    calculating a statistical likelihood of a fetal copy number variation in the maternal sample using the estimated relative frequency of the first and second target genomic regions in the sample and the fraction of fetal DNA.

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