从TCGA下载的甲基化数据是包含了样品中不同甲基化位点的甲基化程度β值和位点的注释信息。该数据的表头解释如下：
| Composite Element | A unique ID for the array probe associated with a CpG site |
| Beta Value | Represents the ratio between the methylated array intensity and total array intensity, falls between 0 (lower levels of methylation) and 1 (higher levels of methylation) |
| Chromosome | The chromosome in which the probe binding site is located |
| Start | The start of the CpG site on the chromosome |
| End | The end of the CpG site on the chromosome |
| Gene Symbol | The symbol for genes associated with the CpG site. Genes that fall within 1,500 bp upstream of the transcription start site (TSS) to the end of the gene body are used. |
| Gene Type | A general classification for each gene (e.g. protein coding, miRNA, pseudogene) |
| Transcript ID | Ensembl transcript IDs for each transcript associated with the genes detailed above |
| Position to TSS | Distance in base pairs from the CpG site to each associated transcript's start site |
| CGI Coordinate | The start and end coordinates of the CpG island associated with the CpG site |
| Feature Type | The position of the CpG site in reference to the island: Island, N_Shore or S_Shore (0-2 kb upstream or downstream from CGI), or N_Shelf or S_Shelf (2-4 kbp upstream or downstream from CGI) |
如果您想学习TCGA数据挖掘，请学习的我TCGA系列课程：
《TCGA-甲基化生存分析》
《TCGA-生存分析》
《TCGA-基因差异表达分析》
《TCGA-ceRNA调控网络分析》
《TCGA-转录因子调控》
