US6807490

Method for DNA mixture analysis

The present invention pertains to a process for automatically analyzing nucleic acid samples. Specifically, the process comprises the steps of forming electrophoretic data of DNA samples with DNA ladders; comparing these data; transforming the coordinates of the DNA sample's data into DNA length coordinates; and analyzing the DNA sample in length coordinates. This analysis is useful for automating fragment analysis and quality assessment. The automation enables a business model based on usage, since it replaces (rather than assists) labor. This analysis also provides a mechanism whereby data generated on different instruments can be confidently compared. Genetic applications of this invention include gene discovery, genetic diagnosis, and drug discovery. Forensic applications include identifying people and their relatives, catching perpetrators, analyzing DNA mixtures, and exonerating innocent suspects.

1. A method for analyzing a DNA mixture comprised of the steps:
   1. obtaining DNA profile data of a sample that comprises a DNA mixture of two or more individuals;
   2. representing the data and a genotype of the individuals contained in the DNA mixture in a set of linear equations;
   3. deriving a mathematical solution by performing a matrix operation on the linear equations; and
   4. determining the genotype at a locus of an individual contained in the DNA mixture from the mathematical solution.
2. A method as described in claim 1 wherein the obtaining step (a) includes the step of performing a PCR on an STR locus of an individual.
3. A method as described in claim 1 wherein the representing step (b) includes a matrix or vector representation of the set of linear equations.
4. A method as described in claim 3 wherein the matrix representation has a term that includes a matrix multiplication of a genotype matrix and a weight matrix.
5. A method as described in claim 1 wherein the deriving step (c) includes an optimization procedure.
6. A method as described in claim 5 wherein the optimization procedure includes a minimization step.
7. A method as described in claim 5 wherein the optimization procedure includes an arithmetic operation.
8. A method as described in claim 1 wherein the determining step (d) produces an estimate of the genotype of an individual.
9. A method as described in claim 8 wherein after the determining step (d), the estimated genotype is matched against a suspect genotype.
10. A method as described in claim 9 wherein the suspect genotype is drawn from a database of candidate suspect genotypes.
11. A method as described in claim 9 wherein the suspect is a likely perpetrator of a crime.
12. A method as described in claim 1 wherein the determining step (d) produces an estimate of a proportion or weight of an individual's DNA contained in the DNA structure.
13. A method as described in claim 1 wherein the determining step (d) produces an estimate of the quality of the determined solution.
14. A method as described in claim 1 wherein the determining step (d) jointly produces both an estimate of a proportion or weight of an individual's DNA contained in the DNA mixture and an estimate of the genotype of the individual.