Patent ID: 8688388

Claim:
A system comprising one or more microprocessors and memory, which memory comprises instructions executable by the one or more microprocessors, and which instructions executable by the one or more microprocessors are configured to: (a) sum counts of nucleotide sequence reads mapped to a subset of genomic sections in the Y chromosome of a reference genome and compare the summed counts to a median count for genomic sections in the Y chromosome for a test sample from a pregnant female bearing a fetus, thereby generating a comparison, wherein: the sequence reads are reads of circulating cell-free nucleic acid from the sample; the subset of genomic sections in the Y chromosome comprises a plurality of genomic sections comprising: i) genomic sections having a consistent number of count totals greater than or equal to 1 for mapped sequence reads from samples from pregnant females carrying male fetuses; ii) genomic sections having a consistent number of counts for mapped sequence reads from samples from pregnant females carrying female fetuses; and iii) genomic sections having a significant and consistent difference of mapped sequence read counts between samples from pregnant females carrying male fetuses and samples from pregnant females carrying female fetuses; and the subset of genomic sections in the Y chromosome does not include selected genomic sections in the Y chromosome, which selected genomic sections in the Y chromosome, when removed from the subset, result in an increase in a separation gap between male and female fetuses greater than or equal to the value Îµ=1%; and (b) determine fetal gender according to the comparison.