MASSIVELY PARALLEL SEQUENCING OF RANDOM DNA FRAGMENTS FOR DETERMINATION OF FETAL FRACTION

摘要

The present invention provides methods for determining the fraction of fetal DNA in a maternal sample using massively parallel shotgun sequencing techniques and statistical probability calculations. The invention utilizes a novel method of identifying polymorphisms through the sequencing process that align to designated regions in the genome. By identifying a statistically significant number of such polymorphisms in multiple designated regions across the genome the fetal fraction, or estimation thereof, can be determined. In certain aspects, the observed distribution of polymorphisms in the genome of a maternal sample can be compared to a fetal proportion reference to estimate the fetal fraction in the sample.

主权项

1. A method for determining fetal fraction in a maternal sample, wherein the method comprises:
a. obtaining a mixture of fetal and maternal genomic DNA from said maternal sample; b. conducting massively parallel DNA sequencing of random DNA fragments from the mixture of fetal and maternal genomic DNA of step a) to determine the sequence of said DNA fragments; c. identifying nucleic acids corresponding to a plurality of informative single nucleotide polymorphisms in designated regions of the genomic DNA by alignment of the sequenced DNA fragments to a reference; d. determining the relative frequency of the sequenced informative single nucleotide polymorphisms; and e. calculating the fetal fraction of the maternal sample using the relative frequency of the sequenced informative single nucleotide polymorphisms.