Processes for calculating phased fetal genomic sequences
The present invention provides processes for calculating phased genomic sequences of the fetal genome using fetal DNA obtained from a maternal sample. The processes and systems of the present invention utilize novel technological and computational approaches to detect fetal genomic sequences and determine the phased heritable genomic sequences. The invention could be used, e.g., to identify in utero deleterious mutations carried by the parents and inherited by a fetus within a particular heritable genomic region.
1. A computer-implemented process for determining the phased composition in a fetal heritable genomic region from a maternal sample comprising maternal DNA and fetal DNA, the process comprising the steps of:
isolating cell-free nucleic acids from the maternal sample comprising the maternal DNA and the fetal DNA, wherein the cell-free nucleic acids comprise selected nucleic acid regions;
interrogating the selected nucleic acid regions in the fetal heritable genomic region using oligonucleotides to amplify the selected nucleic acid regions, the oligonucleotides comprising universal amplification sequences;
applying the amplified selected nucleic acid regions to an array-based pull-out detection system to identify informative loci corresponding to a heritable genomic region of interest;
providing, to a computer processor, phased sequence information from a maternal genome and a paternal genome on at least one corresponding parental heritable genomic region;
masking, by the computer processor, sequence information on loci of the parental heritable genomic region that are indistinguishable between the maternal genome and the paternal genome;
providing, by the computer processor, empirical sequence information on five or more informative loci from the maternal sample corresponding to the heritable genomic region of interest;
calculating, by the computer processor, a predicted paternal contribution of the heritable genomic region of interest using the empirical sequence information of the five or more informative loci;
calculating, by the computer processor, a predicted maternal contribution of the heritable genomic region of interest using the empirical sequence information; and
generating, by the computer processor, a likelihood value of the fetal heritable genomic region contributed by a maternal source and/or a paternal source using the predicted maternal contribution and the predicted paternal contribution of the heritable genomic region of interest.
2. The process of claim 1 , wherein the maternal sample is maternal plasma or serum.
3. The process of claim 1 , wherein the phased sequence information of the parental heritable genomic region is determined by sequencing of the maternal genome and the paternal genome.
4. The process of claim 1 , wherein a fetal genetic variation within the fetal heritable genomic region is imputed from a subset of parental informative loci.
5. The process of claim 1 , wherein the phased sequence information of the at least one corresponding parental heritable genomic region is determined by pedigree analysis.
6. The process of claim 1 , wherein the phased sequence information from a fetal source comprises sequence information on at least twenty informative loci in the fetal heritable genomic region.
7. The process of claim 1 , wherein the fetal heritable genomic region comprises a sub-chromosomal unit.
8. A computer-implemented process to calculate a value of likelihood for
a fetal heritable genomic region from a maternal sample comprising maternal DNA and fetal
DNA, the process, comprising:
isolating cell-free nucleic acids from the maternal sample comprising the maternal DNA and the fetal DNA, wherein the cell-free nucleic acids comprise selected nucleic acid regions;
interrogating the selected nucleic acid regions in the fetal heritable genomic region using oligonucleotides to amplify the selected nucleic acid regions, the oligonucleotides comprising universal amplification sequences;
applying the amplified selected nucleic acid regions to an array-based pull-out detection system to identify informative loci corresponding to a heritable genomic region of interest;
providing, to a computer processor, maternal sequence information and paternal sequence information for a parental heritable genomic region;
providing, by the computer processor, empirical sequence information from the heritable genomic region of interest, wherein the empirical sequence information is obtained from the maternal sample using massively parallel sequencing;
identifying, by the computer processor, at least five informative loci within the parental heritable genomic region;
calculating, by the computer processor, a value of the likelihood of the fetal heritable genomic region inherited by a paternal source using the at least five informative loci and the empirical sequence information;
identifying, by the computer processor, at least five loci that are maternally and paternally heterozygous;
calculating, by the computer processor, a value of the likelihood of the fetal heritable genomic region inherited by a maternal source using the value of the likelihood of the fetal heritable genomic region inherited by the paternal source and the empirical sequence information on the at least five loci that are maternally and paternally heterozygous.
9. The process of claim 8 , wherein the maternal sample is a cell free maternal sample.
10. The process of claim 9 , wherein the cell free maternal sample is maternal plasma or serum.
11. The process of claim 8 , wherein the maternal sample comprises fetal cells.
12. The process of claim 8 , wherein phased sequence information of the parental heritable genomic region is determined by sequencing of a maternal genome and a paternal genome.
13. The process of claim 8 , wherein a fetal genetic variation within the fetal heritable genomic region is imputed from a subset of parental informative loci.
14. The process of claim 8 , wherein phased sequence information of the parental heritable genomic region is determined by pedigree analysis.
15. The process of claim 8 , wherein phased sequence information from a fetal source comprises sequence information on at least twenty informative loci in the fetal heritable genomic region.
16. The process of claim 8 , wherein phased sequence information from a fetal source comprises sequence information on at least fifty informative loci in the fetal heritable genomic region.
17. The process of claim 8 , wherein phased sequence information from a fetal source comprises sequence information on at least one hundred informative loci in the fetal heritable genomic region.
18. The process of claim 8 , wherein the fetal heritable genomic region comprises a sub-chromosomal unit.
19. The process of claim 8 , wherein the fetal heritable genomic region comprises an entire chromosome.
20. The process of claim 8 , wherein the fetal heritable genomic region comprises the entire genome.