0 Posted 2022-12-06Updated 2023-06-06Biology / Bioinformatics / Database7 minutes read (About 980 words)

TCGA Database with R

TCGA Database

Reference:

library(TCGAbiolinks)
library(SummarizedExperiment)
library(dplyr)
library(DT)

projects <- TCGAbiolinks:::getGDCprojects()$project_id
projects <- projects[grepl('^TCGA',projects,perl=T)]

query <- GDCquery(project = projects,
                  data.category = "Transcriptome Profiling",  
                  data.type = "Gene Expression Quantification",  
                  workflow.type = "STAR - Counts")
# counts <- GDCprepare(query,save = TRUE, save.filename = "all_tumor_htseq_raw_counts.rda")
data <- GDCprepare(query = query)

# download and fetch the data from local
GDCdownload(query = query,
              method = "api",
              files.per.chunk = 60,
              directory = "mRNA")

expdat <- GDCprepare(query = query,
                       directory = "mRNA")

If you download successfully, you would see the red codes below.


--------------------------------------
o GDCquery: Searching in GDC database
--------------------------------------
Genome of reference: hg38
--------------------------------------------
oo Accessing GDC. This might take a while...
--------------------------------------------
ooo Project: TCGA-ESCA
ooo Project: TCGA-SARC
ooo Project: TCGA-CESC
ooo Project: TCGA-UCEC
--------------------
oo Filtering results
--------------------
ooo By data.type
ooo By workflow.type
----------------
oo Checking data
----------------
ooo Checking if there are duplicated cases
ooo Checking if there are results for the query
-------------------
o Preparing output
-------------------

Check the group and counts information

# Check the mate information
as.data.frame(colData(data))
# Check Exression counts
assay(data)[1:6,1:4]

TCGA-DX-A6Z0-01A-13R-A36F-07 TCGA-X2-A95T-01A-11R-A37L-07 TCGA-DX-A6BF-01A-11R-A30C-07 TCGA-DX-A1L1-01A-11R-A24X-07
ENSG00000000003.15                         3415                          861                          316                         4004
ENSG00000000005.6                           340                            4                           14                            0
ENSG00000000419.13                         2296                          905                          938                         3935
ENSG00000000457.14                          594                          454                           85                          595
ENSG00000000460.17                          626                          318                           62                          458
ENSG00000000938.13                          259                          138                          271                          381

why download data

Sometimes, you may receive errors:

Error in GDCquery(project = projects[3], data.category = "Transcriptome Profiling",  :
  Please set a valid workflow.type argument from the list below:
  => STAR - Counts

You can’t turn the “GDCprepare” results into data directly. You need to download it first and convert it by “GDCprepare”. See details in github

Differential Expression Genes

Reference: rdrr.io

I am failed to get the expression matrix by using GDCprepare. According to [© g27182818, 2022], it caused by STAR-Count files has more infor than GDCprepare need. What ever, a modified solution could be like codes below:

library('TCGAbiolinks')
library(stringr)

project_name <- "TCGA-CHOL"

# Defines the query to the GDC
query <- GDCquery(project = project_name,
                  data.category = "Transcriptome Profiling",
                  data.type = "Gene Expression Quantification",
                  experimental.strategy = "RNA-Seq",
                  workflow.type = "STAR - Counts")

# Get metadata matrix
metadata <- query[[1]][[1]]

# Get main directory where data is stored
main_dir <- file.path("mRNA", project_name)
# Get file list of downloaded files
file_list <- file.path("mRNA", project_name,list.files(main_dir,recursive = TRUE)) 

# Read first downloaded to get gene names
test_tab <- read.table(file = file_list[1], sep = '\t', header = TRUE)
# Delete header lines that don't contain usefull information
test_tab <- test_tab[-c(1:4),]
# STAR counts and tpm datasets
tpm_data_frame <- data.frame(test_tab[,1])
count_data_frame <- data.frame(test_tab[,1])

# Append cycle to get the complete matrix
for (i in c(1:length(file_list))) {
  # Read table
  test_tab <- read.table(file = file_list[i], sep = '\t', header = TRUE)
  # Delete not useful lines
  test_tab <- test_tab[-c(1:4),]
  # Column bind of tpm and counts data
  tpm_data_frame <- cbind(tpm_data_frame, test_tab[,7])
  count_data_frame <- cbind(count_data_frame, test_tab[,4])
  # Print progres from 0 to 1
  print(i/length(file_list))
}

ID_list <- as.data.frame(str_split_fixed(file_list, '/', 7))[[6]]

row.names(count_data_frame) <- count_data_frame[[1]]
count_data_frame <- count_data_frame[-1]
colnames(count_data_frame) <- metadata$cases[match(ID_list, metadata$id)]

N_control = length(which(as.numeric(gsub("[^0-9.-]", "", as.data.frame(str_split_fixed(metadata$cases, '-', 5))[[4]])) >= 10))

The meaning of the barcode


© NIH, GDC

Label	Identifier for	Value	Value Description	Possible Values
Analyte	Molecular type of analyte for analysis	D	The analyte is a DNA sample	See Code Tables Report
Plate	Order of plate in a sequence of 96-well plates	182	The 182nd plate	4-digit alphanumeric value
Portion	Order of portion in a sequence of 100 - 120 mg sample portions	1	The first portion of the sample	01-99
Vial	Order of sample in a sequence of samples	C	The third vial	A to Z
Project	Project name	TCGA	TCGA project	TCGA
Sample	Sample type	1	A solid tumor	Tumor types range from 01 - 09, normal types from 10 - 19 and control samples from 20 - 29. See Code Tables Report for a complete list of sample codes
Center	Sequencing or characterization center that will receive the aliquot for analysis	1	The Broad InstituteGCC	See Code Tables Report
Participant	Study participant	1	The first participant from MD Anderson for GBM study	Any alpha-numeric value
TSS	Tissue source site	2	GBM (brain tumor) sample from MD Anderson	See Code Tables Report

So, the most important information for us is the sample type: Tumor types range from 01 - 09, normal types from 10 - 19 and control samples from 20 - 29. See Code Tables Report for a complete list of sample codes

Abbreviations of projects

Study Abbreviation	Study Name
LAML	Acute Myeloid Leukemia
ACC	Adrenocortical carcinoma
BLCA	Bladder Urothelial Carcinoma
LGG	Brain Lower Grade Glioma
BRCA	Breast invasive carcinoma
CESC	Cervical squamous cell carcinoma and endocervical adenocarcinoma
CHOL	Cholangiocarcinoma
LCML	Chronic Myelogenous Leukemia
COAD	Colon adenocarcinoma
CNTL	Controls
ESCA	Esophageal carcinoma
FPPP	FFPE Pilot Phase II
GBM	Glioblastoma multiforme
HNSC	Head and Neck squamous cell carcinoma
KICH	Kidney Chromophobe
KIRC	Kidney renal clear cell carcinoma
KIRP	Kidney renal papillary cell carcinoma
LIHC	Liver hepatocellular carcinoma
LUAD	Lung adenocarcinoma
LUSC	Lung squamous cell carcinoma
DLBC	Lymphoid Neoplasm Diffuse Large B-cell Lymphoma
MESO	Mesothelioma
MISC	Miscellaneous
OV	Ovarian serous cystadenocarcinoma
PAAD	Pancreatic adenocarcinoma
PCPG	Pheochromocytoma and Paraganglioma
PRAD	Prostate adenocarcinoma
READ	Rectum adenocarcinoma
SARC	Sarcoma
SKCM	Skin Cutaneous Melanoma
STAD	Stomach adenocarcinoma
TGCT	Testicular Germ Cell Tumors
THYM	Thymoma
THCA	Thyroid carcinoma
UCS	Uterine Carcinosarcoma
UCEC	Uterine Corpus Endometrial Carcinoma
UVM	Uveal Melanoma