Project description:Methods of comprehensive microarray based analyses of single cell DNA are rapidly emerging. Whole genome amplification (WGA) remains a critical component for these methods to be successful. A number of commercially available WGA kits have been independently utilized in previous single cell microarray studies. However, direct comparison of their performance on single cells has not been conducted. The present study demonstrates that among previously published methods, a single cell GenomePlex WGA protocol provides the best combination of speed and accuracy for SNP microarray based copy number analysis when compared to a REPLI-g or GenomiPhi based protocol. Alternatively, for applications that do not have constraints on turn-around time and that are directed at accurate genotyping rather than copy number assignments, a REPLI-g based protocol may provide the best solution.
Project description:Methods of comprehensive microarray based analyses of single cell DNA are rapidly emerging. Whole genome amplification (WGA) remains a critical component for these methods to be successful. A number of commercially available WGA kits have been independently utilized in previous single cell microarray studies. However, direct comparison of their performance on single cells has not been conducted. The present study demonstrates that among previously published methods, a single cell GenomePlex WGA protocol provides the best combination of speed and accuracy for SNP microarray based copy number analysis when compared to a REPLI-g or GenomiPhi based protocol. Alternatively, for applications that do not have constraints on turn-around time and that are directed at accurate genotyping rather than copy number assignments, a REPLI-g based protocol may provide the best solution. Affymetrix SNP arrays were processed according to the manufacturer's directions on DNA extracted from human fibroblast cell lines and single fibroblast cells. Afflymetrix SNP array analysis was successfully completed on 46 lymphocyte single cell samples, 8 gDNA extracted from cell lines, 11 reference gDNA extracted from cell lines and 3 reference gDNA samples from the RMA of New Jersey DNA bank. GSM617116 to GSM617129: CEL files were processed using GTYPE version 4 (Affymetrix Inc., Genotyping Console 4.0 Manual) using the DM algorithm for genotype calls. Copy number and loss of heterozygosity were calculated from CHP files using CNAT version 4.1 (Affymetrix Inc., Genotyping Console 4.0 Manual) analysis against a reference set consisting of three normal females from in house gDNA bank, 11 normal females from Coriel cell lines and 16 normal females from the HapMap database (www.hapmap.org). The 16 normal females are NA10855, NA10863, NA11832, NA12057, NA12234, NA12717, NA12813, NA18505, NA18508, NA18517, NA19137, NA19152, NE00088, NE00091, NE00403, and NE01119.
Project description:Copy number analysis of human GBM samples were performed, and a high frequency of deletions of the PTPRD gene on chromosome 9p23-24.1 were identified. Keywords: SNP microarray, glioblastoma multiforme, copy number, amplification, deletion
Project description:Genome-wide SNP genotyping array can genotyped SNP highthroughly. It can be used in many aspects, such as phylogeny relationships, genome-wide association studies, copy number identification.
Project description:DNA copy number changes with or without accompanying copy neutral changes such as unparental disomy (UPD) is a feature of the cancer genome that is linked to cancer development. However, technical problems with archived formalin-fixed, paraffin-embedded (FFPE) tissue samples have limited their general use in genomic profiling studies done using high-density single nucleotide polymorphism (SNP) microarray. To overcome the current problems with the use of this material in the detection of DNA copy number and copy neutral changes, we have devised two new protocols for extracting DNA from FFPE tissue. Genotyping efficiency and accuracy were improved using our novel protocols. After censoring the larger fragments, we obtained call rates for FFPE DNA equivalent to those for FF tissue DNA, with concordance rates between FFPE and FF tumor exceeding 99%. Identical DNA copy number changes were obtained for FFPE and FF; and between two new extraction protocols in tumor samples by using Affymetrix® high-density oligo-based SNP microarray platform. We observed UPD and recurrent gains and losses in tumor samples. Interestingly, we also identified UPD in the 5q and 13q regions in matching normal blood, FF adjacent breast tissue and tumor tissue in two samples. In conclusion, our new two DNA extraction protocols should substantially improve the ability to use archived material to help elucidate the complexity of early-stage breast cancer genomes. Keywords: SNP based array
Project description:Generating sufficient DNA for high-throughput genetic analysis has always been a challenge for clinical settings where the amount of source DNA is limited. Multiple displacement amplification (MDA) has been proposed as a promising candidate for such situations. Previous work with lower-resolution arrays confirmed the utility of single-cell MDA products for large-size (~30 Mb) genome variation screening. We tested the performance of single-cell MDA products on the SNP 6.0 arrays to examine the performance of single-cell MDA in SNP genotyping, copy number polymorphism, de novo copy number variation (CNV) and loss of heterozygosity (LOH) analysis. Our data show that for SNP genotyping, single-cell MDA did not obtain complete genome coverage or high sequence fidelity. For CNV calling, single-cell MDA introduced stochastic amplification artifacts in log2 ratio profiles, reducing the robustness of CNV calling; however, by adjusting smooth window size, it is still possible to analyze large chromosomal aberrations, and homozygous deletions as small as 500 kb can still be identified from the noisy log2 ratio profiles. Our results also suggest that even with a modified protocol (reduction of reaction volume, addition of a molecular crowding reagent, minimization of reaction time), single-cell MDA presented little improvement over the unmodified protocol, but by increasing the number of cells as template to 5M-bM-^@M-^S10 cells, SNP 6.0 array results comparable to those of 10 ng genomic DNA MDA could be obtained. Algorithms like PICNIC improved the CNV calling, suggesting that better algorithms can better utilize single-cell MDA array results. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from cell line samples, and multiple displacement samples. Genotyping, Copy number and LOH analysis of Affymetrix SNP 6.0 arrays was performed for 3 samples of unamplified cell line genomic DNA, 2 samples of DNA obtained by multiple displacement amplification from 10ng genomic DNA, 3 single-cell multiple displacement amplification (MDA) products, single cell modified MDA amplification product, 5-cell modified MDA amplification product, 10-cell modified MDA amplification product.
Project description:Renal tumors with complex morphology require extensive workup for accurate classification. Chromosomal aberrations that define subtypes of renal epithelial neoplasms have been reported. We explored if whole-genome chromosome copy number and loss-of-heterozygosity analysis with single nucleotide polymorphism (SNP) arrays can be used to identify these aberrations. Keywords: Chromosome copy number and LOH analysis with SNP Genotyping Arrays
Project description:Renal tumors with complex morphology require extensive workup for accurate classification. Chromosomal aberrations that define subtypes of renal epithelial neoplasms have been reported. We explored if whole-genome chromosome copy number and loss-of-heterozygosity analysis with single nucleotide polymorphism (SNP) arrays can be used to identify these aberrations in cases where morphology was unable to definitively classify these tumors. Keywords: Chromosome copy number and LOH analysis (virtual karyotyping) with SNP Genotyping Arrays Keywords: Genome variation profiling by SNP array
Project description:Generating sufficient DNA for high-throughput genetic analysis has always been a challenge for clinical settings where the amount of source DNA is limited. Multiple displacement amplification (MDA) has been proposed as a promising candidate for such situations. Previous work with lower-resolution arrays confirmed the utility of single-cell MDA products for large-size (~30 Mb) genome variation screening. We tested the performance of single-cell MDA products on the SNP 6.0 arrays to examine the performance of single-cell MDA in SNP genotyping, copy number polymorphism, de novo copy number variation (CNV) and loss of heterozygosity (LOH) analysis. Our data show that for SNP genotyping, single-cell MDA did not obtain complete genome coverage or high sequence fidelity. For CNV calling, single-cell MDA introduced stochastic amplification artifacts in log2 ratio profiles, reducing the robustness of CNV calling; however, by adjusting smooth window size, it is still possible to analyze large chromosomal aberrations, and homozygous deletions as small as 500 kb can still be identified from the noisy log2 ratio profiles. Our results also suggest that even with a modified protocol (reduction of reaction volume, addition of a molecular crowding reagent, minimization of reaction time), single-cell MDA presented little improvement over the unmodified protocol, but by increasing the number of cells as template to 5–10 cells, SNP 6.0 array results comparable to those of 10 ng genomic DNA MDA could be obtained. Algorithms like PICNIC improved the CNV calling, suggesting that better algorithms can better utilize single-cell MDA array results.
Project description:Single-cell human genome analysis using whole-genome amplified product is hampered by allele bias during amplification. Using an oligonucleotide SNP array, we examined the nature of the allele bias and its effect on the chromosomal copy number analysis. Keywords: single cell, copy number analysis, whole genome amplification, brain