Patent Document ID: 20120270212
Application ID: 13300235
Patent Flag: 0

Claim One:
1. A method for determining a ploidy status of a chromosome in a gestating fetus, the method comprising: obtaining a first sample of DNA that comprises maternal DNA from the mother of the fetus and fetal DNA from the fetus; preparing the first sample by isolating the DNA so as to obtain a prepared sample; measuring the DNA in the prepared sample at a plurality of polymorphic loci on the chromosome; calculating, on a computer, allele counts at the plurality of polymorphic loci from the DNA measurements made on the prepared sample; creating, on a computer, a plurality of ploidy hypotheses each pertaining to a different possible ploidy state of the chromosome; building, on a computer, a joint distribution model for the expected allele counts at the plurality of polymorphic loci on the chromosome for each ploidy hypothesis; determining, on a computer, a relative probability of each of the ploidy hypotheses using the joint distribution model and the allele counts measured on the prepared sample; and calling the ploidy state of the fetus by selecting the ploidy state corresponding to the hypothesis with the greatest probability.