D reverse primer mix (Table 2), 1 ml cDNA (100 ng/ml), 0.1 ml of rTaq, 0.5 ml of fluorochrome (TIANGEN BIOTECH) and 5.15 ml of ddH2O.Results Case and ControlUsing 18 solid tumors 
from patients (9 as LGG and 9 as HGG) as the case sample and the patients’ DNA isolated from their peripheral blood as the control, we compared chromosome aberrations between the case and control based on the Illumina’s BIBS39 chemical information BeadChip platform that defines both copy number variation (CNVs) and copy neutral loss of heterozygosity (cnLOH). This technology allows us to find sequence differences between tumor and blood samples at cytogenetic and molecular levels, which include both gains and losses. We only discovered sequence amplifications in the tumor not in the corresponding periphery blood. In other three aberration categories of CNVs, there are always more variations in the tumor than in the control, and the significance of variations between the paired samples can be evaluated statistically (P-value,0.05, paired t-test) when the total length influenced by CNVs in each sample was considered.cnLOHsL 15481974 L L H H H H H H H HDuplicationsL L L L L L L H H HCNVs among Autosomal ArmsAfter the survey of different CNVs in 44 autosomal arms in LGG and HGG, we removed those shared by tumors and their controls to identify tumor-specific variations. We made a few interesting observations. First, 13q harbors a major high-frequency genomic aberration class. For instance, there are 3, 3, 3, 2, and 2 samples found to have homozygous deletion, hemizygous deletion, cnLOHs, duplication and amplification, respectively. Second, we found that 22, 29, 38, 38, and 6 chromosomal arms have variations in the five categories, respectively. Obviously, cnLOH is one of the most frequent categories, and our results agreed with a previous report [43]. In addition, the skewed distribution of sequence amplification showed that there were more copy number gains found on only a few chromosomal arms. Third, we paid more attention to CNVs between LGG and HGG and found several homozygous deletions of 13q in HGG but not in LGG. There were also cnLOHs in three HGG, such as those on 15q and 17q, but none was found in LGG. In addition, four HGG had duplications on 3q but none was found in LGG.AmplificationsHNote: L and H stand for LGG and HGG, respectively. doi:10.1371/journal.pone.0057168.tCNV370-Quad v3 BeadChip according to the manufacturer’s instruction.Data Analysis and Functional AnnotationIllumina’s KaryoStudio (V1.0.3), together with the cnvPartition IQ-1 algorithm, was adopted to identify CNV regions. Illumina’s GenomeStudio software (V2009.1) with LOHscore plug-in was used to discover copy neutral loss of heterozygosity (cnLOH) regions. The samples were divided into LGG and HGG, and the analysis was limited to autosomal regions only due to the experiment design. The data used in this study were submitted to GEO with an accession of GSE34888.Comparison of LGG and HGG at the Cytoband LevelTo pinpoint the position of variations on chromosomes, we investigated CNV and cnLOH in LGG and HGG. To reduce false positives, we only referred to those that occurred in at least two tumor samples (four samples for “duplications” category) after removing what appeared in the controls, i.e., corresponding blood samples (Table 3). Taking homozygous deletion as an example, we found several events on 8p11.23 in LGG, and 13q12.11 in HGG. In both hemizygous deletion and cnLOH, we found more cytobands in HGG than in LGG. Surprisi.D reverse primer mix (Table 2), 1 ml cDNA (100 ng/ml), 0.1 ml of rTaq, 0.5 ml of fluorochrome (TIANGEN BIOTECH) and 5.15 ml of ddH2O.Results Case and ControlUsing 18 solid tumors from patients (9 as LGG and 9 as HGG) as the case sample 
and the patients’ DNA isolated from their peripheral blood as the control, we compared chromosome aberrations between the case and control based on the Illumina’s BeadChip platform that defines both copy number variation (CNVs) and copy neutral loss of heterozygosity (cnLOH). This technology allows us to find sequence differences between tumor and blood samples at cytogenetic and molecular levels, which include both gains and losses. We only discovered sequence amplifications in the tumor not in the corresponding periphery blood. In other three aberration categories of CNVs, there are always more variations in the tumor than in the control, and the significance of variations between the paired samples can be evaluated statistically (P-value,0.05, paired t-test) when the total length influenced by CNVs in each sample was considered.cnLOHsL 15481974 L L H H H H H H H HDuplicationsL L L L L L L H H HCNVs among Autosomal ArmsAfter the survey of different CNVs in 44 autosomal arms in LGG and HGG, we removed those shared by tumors and their controls to identify tumor-specific variations. We made a few interesting observations. First, 13q harbors a major high-frequency genomic aberration class. For instance, there are 3, 3, 3, 2, and 2 samples found to have homozygous deletion, hemizygous deletion, cnLOHs, duplication and amplification, respectively. Second, we found that 22, 29, 38, 38, and 6 chromosomal arms have variations in the five categories, respectively. Obviously, cnLOH is one of the most frequent categories, and our results agreed with a previous report [43]. In addition, the skewed distribution of sequence amplification showed that there were more copy number gains found on only a few chromosomal arms. Third, we paid more attention to CNVs between LGG and HGG and found several homozygous deletions of 13q in HGG but not in LGG. There were also cnLOHs in three HGG, such as those on 15q and 17q, but none was found in LGG. In addition, four HGG had duplications on 3q but none was found in LGG.AmplificationsHNote: L and H stand for LGG and HGG, respectively. doi:10.1371/journal.pone.0057168.tCNV370-Quad v3 BeadChip according to the manufacturer’s instruction.Data Analysis and Functional AnnotationIllumina’s KaryoStudio (V1.0.3), together with the cnvPartition algorithm, was adopted to identify CNV regions. Illumina’s GenomeStudio software (V2009.1) with LOHscore plug-in was used to discover copy neutral loss of heterozygosity (cnLOH) regions. The samples were divided into LGG and HGG, and the analysis was limited to autosomal regions only due to the experiment design. The data used in this study were submitted to GEO with an accession of GSE34888.Comparison of LGG and HGG at the Cytoband LevelTo pinpoint the position of variations on chromosomes, we investigated CNV and cnLOH in LGG and HGG. To reduce false positives, we only referred to those that occurred in at least two tumor samples (four samples for “duplications” category) after removing what appeared in the controls, i.e., corresponding blood samples (Table 3). Taking homozygous deletion as an example, we found several events on 8p11.23 in LGG, and 13q12.11 in HGG. In both hemizygous deletion and cnLOH, we found more cytobands in HGG than in LGG. Surprisi.
