Guardant Health, Inc.

Grail, Inc.

Verinata Health, Inc.

Life Technologies Corporation

Veracyte, Inc.

Catalin Barbacioru

Darya Chudova

Marcin Sikora

Richard P Rava

David A Comstock

Sven Duenwald

Keith W Jones

Gengxin Chen

Dimitri Skvortsov

Aliaksandr Artsiomenka

Martina I Lefterova

Onur Sakarya

Qinwen Liu

Ling Shen

A system and a method are described for applying a noise model for predicting the occurrence and a level of noise that is present in cfDNA read information. The significance model is trained for a plurality of stratifications of called variants using training data in the stratification. Stratifications may include a partition and a mutation type. The significance model predicts the likelihood of observing a read frequency for a called variant in view of two distributions of the significance model. The first distribution predicts a likelihood of noise occurrence in the sample. The second distribution predicts a likelihood of observing a magnitude of the read frequency for the called variant. The two distributions may further depend on a baseline noise level of blank samples. With these two distributions, the significance model, for a particular stratification, more accurately predicts the likelihood of a false positive for a called variant.

Identifying false positive variants using a significance model

Provided herein are methods for determining the microsatellite instability status of samples. In one aspect, the methods include quantifying a number of different repeat lengths present at each of a plurality of microsatellite loci from sequence information to generate a site score for each of the plurality of the microsatellite loci. The methods also include comparing the site score of a given microsatellite locus to a site specific trained threshold for the given microsatellite locus for each of the plurality of the microsatellite loci and calling the given microsatellite locus as being unstable when the site score of the given microsatellite locus exceeds the site specific trained threshold for the given microsatellite locus to generate a microsatellite instability score, which includes a number of unstable microsatellite loci from the plurality of the microsatellite loci.

Microsatellite instability detection in cell-free DNA

The disclosure relates to computer technology for precision diagnosis of various states of genetic material such as a gene sequenced from cell-free DNA in a sample. The state may include a somatic homozygous deletion, a somatic heterozygous deletion, a copy number variation, or other states. A computer system may generate competing probabilistic models that each output a probability that the genetic material is in a certain state. Each model may be trained on a training sample set to output a probability that the genetic material is in a respective state. In some embodiments, the computer system may use various probabilistic distributions to generate the models. For example, the computer system may use a beta-binomial distribution, a binomial distribution, a normal (also referred to as 'Gaussian') distribution, or other type of probabilistic modeling techniques.

Computational modeling of loss of function based on allelic frequency

Gene copy number variations are identified for genes in a targeted gene panel. For each gene, coverage at each base position across the gene is determined. The coverage at each base position can be influenced by the hybridization probes that are used to determine the base level coverage of the base position. The base level coverage for each base position is normalized to account for the characteristics of the hybridization probes. To determine whether a copy number variation exists for a gene, the base level coverage of base positions across the gene for a subject is analyzed to determine whether it deviates from the base level coverage of base positions across the gene for previously analyzed, healthy individuals. If a significant deviation exists, a copy number variation for the gene is called.

Base coverage normalization and use thereof in detecting copy number variation

Cross-contamination of a test sample used to determine cancer is identified using gene sequencing data. Each test sample includes a number of test sequences that may include a single nucleotide polymorphism (SNP) that can be indicative of cancer. The test sequences are be filtered to remove or negate at least some of the SNPs from the test sequences. Negating the test sequences allows more test sequences to be simultaneously analyzed to determine cross-contamination. Cross-contamination is determined by modeling the variant allele frequency for the test sequences as a function of minor allele frequency, contamination level, and background noise. In some cases, the variant allele frequency is based on a probability function including the minor allele frequency. Cross-contamination of the test sample is determined if the determined contamination level is above a threshold and statistically significant.

Detecting cross-contamination in sequencing data using regression techniques

Disclosed are methods for determining copy number variation (CNV) known or suspected to be associated with a variety of medical conditions. In some embodiments, methods are provided for determining copy number variation of fetuses using maternal samples comprising maternal and fetal cell free DNA. In some embodiments, methods are provided for determining CNVs known or suspected to be associated with a variety of medical conditions. Some embodiments disclosed herein provide methods to improve the sensitivity and/or specificity of sequence data analysis by deriving a fragment size parameter. In some implementations, information from fragments of different sizes are used to evaluate copy number variations. In some implementations, one or more t-statistics obtained from coverage information of the sequence of interest is used to evaluate copy number variations. In some implementations, one or more fetal fraction estimates are combined with one or more t-statistics to determine copy number variations.

Using cell-free DNA fragment size to determine copy number variations

Disclosed are methods for determining copy number variation (CNV) known or suspected to be associated with a variety of medical conditions. In some embodiments, methods are provided for determining copy number variation (CNV) of fetuses using maternal samples comprising maternal and fetal cell free DNA. In some embodiments, methods are provided for determining CNVs known or suspected to be associated with a variety of medical conditions. Some embodiments disclosed herein provide methods to improve the sensitivity and/or specificity of sequence data analysis by deriving a fragment size parameter, such as a size-weighted coverage or a fraction of fragments in a size range. In some embodiments, the fragment size parameter is adjusted to remove within-sample GC-content bias. In some embodiments, removal of within-sample GC-content bias is based on sequence data corrected for systematic variation common across unaffected training samples. Also disclosed are systems and computer program products for evaluation of CNV of sequences of interest.

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Fremont, CA, United States of America

Catalin Barbacioru