Genomic exploration of monozygotic twins discordant (MZD) for schizophrenia uncovers de novo mutations (DNM) and reveals candidate genes
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ABSTRACT: We examined six pairs of monozygotic twins discordant (MZD) for schizophrenia and identified copy number variation (CNV) and single nucleotide polymorphism (SNP) differences between affected and unaffected co-twins using the Affymetrix Genome Wide SNP 6.0. Affymetrix SNP arrays were performed according to the manufacurer's protocol on DNA extracted from whole blood CNV analysis was done using Affymetrix Genotyping Console 4.0 and Partek Genotyping Suite
Project description:We examined six pairs of monozygotic twins discordant (MZD) for schizophrenia and identified copy number variation (CNV) and single nucleotide polymorphism (SNP) differences between affected and unaffected co-twins using the Affymetrix Genome Wide SNP 6.0.
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:This SuperSeries is composed of the following subset Series: GSE18642: Definitive SNP/CNV haplotype map of Asians determined using a collection of complete hydatidiform moles (Affymetrix) GSE18663: Definitive SNP/CNV haplotype map of Asians determined using a collection of complete hydatidiform moles (Illumina) Refer to individual Series
Project description:Copy number analysis of Affymetrix GW6.0 SNP/CNV arrays was performed for 7 tumours (4 adrenocortical carcinomas, 2 rhabdomyosarcoma and 1 extra-renal rhabdoid tumour) derived from individuals with germline p53-mutations. Affymetrix CNV/SNP arrays were performed according to the manufacturer's directions on DNA extracted from fresh frozen tumour samples
Project description:A consanguineous family segregating anhidrosis (recessive, familial) Shared homozygous regions were identified by comparing SNP genotyping results from four affected family members Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from peripheral blood samples.
Project description:Comparison of Genotyping using pooled DNA samples (Allelotyping) and Individual Genotyping using the Affymetrix Genome-Wide Human SNP Array 6.0 In this study, data from 100 DNA samples individually genotyped with the Affymetrix Genome-Wide Human SNP Array 6.0 were used to estimate the error of the pooling approach by comparing the results with those obtained using the same array type but DNA pools each composed of 50 of the same samples. Newly developed and established methods for signal intensity correction were applied. Furthermore, the relative allele intensity signals (RAS) obtained by allelotyping were compared to the corresponding values derived from individual genotyping. Similarly, differences in RAS values between pools were determined and compared. 2 disjunct DNA pools each composed of 50 samples, incl. one technical replicate each.
Project description:The ideal genome sequence for medical interpretation is complete and diploid, capturing the full spectrum of genetic variation. Toward this end, there has been progress in discovery of single nucleotide polymorphism (SNP) and small (<10bp) insertion/deletions (indels), but annotation of larger structural variation (SV) including copy number variation (CNV) has been less comprehensive, even with available diploid sequence assemblies. We applied a multi-step sequence and microarray-based analysis to identify numerous previously unknown SVs within the first genome sequence reported from an individual. An Affymetrix SNP array experiment was performed according to the manufacturer's directions on DNA extracted from a lymphoblastoid cell line (HuRef). Copy number analysis of Affymetrix 6.0 SNP arrays was performed for the HuRef sample. The HuRef sample was run in a batch of 50 control samples, which were used as baseline for calling CNVs.
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:Chromosomal abnormalities have been identified in some individuals with Autism Spectrum Disorder (ASD), but their full etiologic role is unknown. Submicroscopic copy number variation (CNV) represents a considerable source of genetic variation in the human genome that contributes to phenotypic differences and disease susceptibility. To explore the contribution CNV imbalances in ASD, we genotyped unrelated ASD index cases using the Affymetrix GeneChip® 500K single nucleotide polymorphism (SNP) mapping array. Keywords: Whole Genome Mapping SNP Genotyping Array
Project description:In order to identify biomarkers that contribute to genetic causes of OSCC, we attempt to identify copy number variation regions (CNV) in patients with OSCC. We identified and confirmed the clinical significance of amplification regions scattered from 8q22.2 to 8q24.3. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from normal oral tissues and OSCC specimens. Copy number analysis of Affymetrix SNP 6.0 arrays was performed for 112 OSCC specimens and 10 non-cancerous samples.