Project description:Proteomic genotyping is the use of genetically variant peptides (GVPs), detected in a forensic protein sample, to infer the genotype of corresponding non-synonymous SNP alleles in the donor’s genome. This process does not depend on the presence of accessible or useable DNA in a sample. This makes proteomic genotyping an attractive alternative for analysis of problematic forensic samples, such as hair shafts, degraded bones or teeth, fingermarks, or sexual assault evidence. To demonstrate the concept in hair shafts, we developed an optimized sample processing protocol that could be used with high effectiveness on single hairs. This allows us to determine if the detected profiles of genetically variant peptides are robust and result in a consistent profile of inferred SNP alleles regardless of the chemical or biological history of the sample. Several real world scenarios have been evaluated. Here we include a study of four European subjects that had both pigmented and non-pigmented (or gray and non-gray) hair shafts. We tested whether (a) protein profiles change as a result of the loss of pigmentation and (b) these changes were reflected in the inferred genotype derived from detection of genetically variant peptides. Using this information, we can determine whether the resulting GVP profiles are more dependent on the biological context of pigmentation status or the underlying genotype.
Project description:A SNP microarray and FISH-based procedure to detect allelic imbalances in multiple myeloma: an integrated genomics approach reveals a wide dosage effect on gene and microRNA expression This SuperSeries is composed of the following subset Series: GSE13591: Integrated genomics approach to detect allelic imbalances in multiple myeloma GSE16121: Integrated genomics approach to detect allelic imbalances in multiple myeloma, SNP data Refer to individual Series
Project description:High-resolution microarray-based whole genome genotyping (WGG) techniques based on SNP analysis have successfully been applied in cancer genomics to study gene copy number alterations and allele-specific aberrations such as loss-of-heterozygosity (LOH). Problems in data interpretation arise when WGG is applied on tumor tissue specimens, in which normal cell components and tumor subpopulations frequently exist. Such heterogeneity may lead to reduced detection of cancer cell specific genomic alterations. To circumvent problems with sample heterogeneity, we propose using a segmentation strategy derived from DNA copy number analysis for detection of LOH and allelic imbalance. We generated an experimental dilution series of a tumor cell line mixed with its paired normal cell line and simulated data for such dilutions to test the strategy. We also used data sets generated on both Affymetrix and Illumina WGG platforms, including paired tumor-normal samples and tumors previously characterized by FISH. We tested the segmentation strategy against several reported algorithms. We demonstrate high sensitivity and specificity of the segmentation strategy for detecting both minute and gross allelic imbalances originating from DNA copy number gain, loss, and neutral events in tumor specimens. For example, hemizygous copy number loss can be detected in samples containing only 20-25% tumor cells. Furthermore, the strategy can identify cell subpopulation specific events and accurately estimate the fraction of cells affected by an allelic imbalance. Thus, the segmentation strategy extends the usefulness of WGG platforms for investigation of allelic imbalances in heterogeneous tumor genomes.
Project description:A SNP microarray and FISH-based procedure to detect allelic imbalances in multiple myeloma: an integrated genomics approach reveals a wide dosage effect on gene and microRNA expression This SuperSeries is composed of the SubSeries listed below.
Project description:Forensic body fluid identification is important for crime scene reconstruction. We used Illumina HumanMethylation 450K bead array containing over the 450,000 CpG sites in 16 body fluid samples to find novel DNA methylation marker for forensic body fluid identification. Examination of genome-wide DNA methylation profiling in 16 body fluid samples
Project description:A SNP microarray and FISH-based procedure to detect allelic imbalances in multiple myeloma: an integrated genomics approach reveals a wide dosage effect on gene and microRNA expression Multiple myeloma (MM) is characterized by marked genomic instability. Beyond structural rearrangements, a relevant role in its biology is represented by allelic imbalances leading to significant variations in ploidy status. To better elucidate the genomic complexity of MM, we analyzed a panel of 45 patients using combined FISH and microarray approaches. Using a self-developed procedure to infer exact local copy numbers for each sample, we identified a significant fraction of patients showing marked aneuploidy. A conventional clustering analysis showed that aneuploidy, chromosome 1 alterations, hyperdiploidy and recursive deletions at 1p and chromosomes 13, 14 and 22 were the main aberrations driving samples grouping. Then, we integrated mapping information with gene and microRNAs expression profiles: a multiclass analysis of the identified clusters showed a marked gene-dosage effect, particularly concerning 1q transcripts, also confirmed by correlating gene expression levels and local copy number alterations. A wide dosage effect affected also microRNAs, indicating that structural abnormalities in MM closely reflect in their expression imbalances. Finally, we identified several loci in which genes and microRNAs expression correlated with loss-of-heterozygosity occurrence. Our results provide insights into the composite network linking genome structure and gene/microRNA transcriptional features in MM. Keywords: Integrated genomics approach based on SNP microarray and FISH procedures to detect allelic imbalances in multiple myeloma.
Project description:Forensic body fluid identification is important for crime scene reconstruction. We used Illumina HumanMethylation 450K bead array containing over the 450,000 CpG sites in 16 body fluid samples to find novel DNA methylation marker for forensic body fluid identification.
Project description:We investigated the allele- and strand-specific transcriptional landscape of a megabase-wide genomic region of mouse Ube3a (ubiquitin protein ligase E3A) by means of a highly parallel SNP genotyping platform. We have successfully identified maternal-specific expression of Ube3a and its antisense counterpart (Ube3a-ATS) in brain, but not in liver. Because of the use of inter-subspecies hybrid mice, this megabase-wide analysis provided high-resolution picture of the transcriptional patterns of this region. First, we showed that brain-specific maternal expression of Ube3a is restricted to the second half part of the locus, but is absent from the first half part. Balance of allelic expression is altered in the middle of the locus. Second, we showed that expression of the brain-specific Ube3a-ATS appeared to be terminated in the region upstream to the Ube3a transcription start site. The present study highlights the importance of locus-wide competition between sense and antisense transcripts.
Project description:Illumina Infinium whole genome genotyping (WGG) arrays are increasingly being applied in cancer genomics to study gene copy number alterations and allele-specific aberrations such as loss-of-heterozygosity (LOH). Methods developed for normalization of WGG arrays have mostly focused on diploid, normal samples. However, for cancer samples genomic aberrations may confound normalization and data interpretation. Therefore, we examined the effects of the conventionally used normalization method for Illumina Infinium arrays when applied to cancer samples. We demonstrate an asymmetry in the detection of the two alleles for each SNP, which deleteriously influences both allelic proportions and copy number estimates. The asymmetry is caused by a remaining bias between the two dyes used in the Infinium II assay after using the normalization method in Illumina’s proprietary software (BeadStudio). We propose a quantile normalization strategy for correction of this dye bias. We tested the normalization strategy using 535 individual hybridizations from 10 data sets from the analysis of cancer genomes and normal blood samples generated on Illumina Infinium II 300k version 1 and 2, 370k and 550k BeadChips. We show that the proposed normalization strategy successfully removes asymmetry in estimates of both allelic proportions and copy numbers. Additionally, the normalization strategy reduces the technical variation for copy number estimates while retaining the response to copy number alterations. The proposed normalization strategy represents a valuable low-level analysis tool that improves the quality of data obtained from Illumina Infinium arrays, in particular when used for LOH and copy number variation studies.