inst/scripts/create_ccvariants.R

In qtl2: Quantitative Trait Locus Mapping in Experimental Crosses

# Create sqlite database with variants (SNPs/indels/SVs)
# in the 8 founder strains of the Collaborative Cross (CC)
######################################################################
# sources:
#   SNPs:
#     ftp://ftp-mouse.sanger.ac.uk/current_snps/mgp.v5.merged.snps_all.dbSNP142.vcf.gz
#     ftp://ftp-mouse.sanger.ac.uk/current_snps/mgp.v5.merged.snps_all.dbSNP142.vcf.gz.tbi
#   Indels:
#     ftp://ftp-mouse.sanger.ac.uk/current_indels/mgp.v5.merged.indels.dbSNP142.normed.vcf.gz
#     ftp://ftp-mouse.sanger.ac.uk/current_indels/mgp.v5.merged.indels.dbSNP142.normed.vcf.gz.tbi
#   SVs:
#     ftp://ftp-mouse.sanger.ac.uk/current_svs/28strains.REL-1410-SV.sdp.tab.gz
#     ftp://ftp-mouse.sanger.ac.uk/current_svs/28strains.REL-1410-SV.sdp.tab.gz.tbi
#
# Same files (except SVs), at JAX:
#   SNPs:
#     ftp://ftp.jax.org/SNPtools/variants/mgp.v5.merged.snps_all.dbSNP142.vcf.gz
#     ftp://ftp.jax.org/SNPtools/variants/mgp.v5.merged.snps_all.dbSNP142.vcf.gz.tbi
#   Indels:
#     ftp://ftp.jax.org/SNPtools/variants/mgp.v5.merged.indels.dbSNP142.normed.vcf.gz
#     ftp://ftp.jax.org/SNPtools/variants/mgp.v5.merged.indels.dbSNP142.normed.vcf.gz.tbi
######################################################################

##############################
### download files
##############################
site <- c("ftp://ftp.jax.org",
          "ftp://ftp.jax.org",
          "ftp://ftp-mouse.sanger.ac.uk")
subdir <- c("SNPtools/variants",
            "SNPtools/variants",
            "current_svs")
files <- c("mgp.v5.merged.snps_all.dbSNP142.vcf.gz",
           "mgp.v5.merged.indels.dbSNP142.normed.vcf.gz",
           "28strains.REL-1410-SV.sdp.tab.gz")
date_source <- c("2015-09-20",
                 "2015-09-20",
                 "2014-10-20")
genome_build <- rep("GRCm38/mm10", 3)

for(i in seq_along(files)) {
    file <- files[i]
    url <- paste0(site[i], "/", subdir[i], "/", file)
    tbi_file <- paste0(file, ".tbi")
    tbi_url <- paste0(site[i], "/", subdir[i], "/", tbi_file)

    if(!file.exists(file)) {
        cat(" -Downloading", file, "\n")
        download.file(url, file)
    }
    if(!file.exists(tbi_file)) {
        cat(" -Downloading", tbi_file, "\n")
        download.file(tbi_url, tbi_file)
    }
}

# function for re-formating snp/indel "consequence"
# Consequences: vectors of |-separated valued
#    2nd value is gene ID
#    3rd is transcript ID (ignored)
#    5th is consequence (potentially with multiple separated by &'s)
format_consequence <-
    function(csq_record)
{
        x <- strsplit(csq_record, "|", fixed=TRUE)
        genes <- sapply(x, "[", 2)
        csq <- sapply(x, "[", 5)
        csq <- unlist(lapply(seq_along(csq),
                             function(i) {
            if(genes[i] == "") {
                return(csq[i])
            } else {
                tmp <- unlist(strsplit(csq[i], "&", fixed=TRUE))
                return(paste(genes[i], tmp, sep=":"))
            }}))
        c(paste(unique(genes), collapse=","),
          paste(unique(csq), collapse=","))
}





##############################
### SNPs
##############################
chr <- c(1:19, "X", "Y", "MT")
cc_founders <- c("A/J", "C57BL/6J", "129S1/SvImJ", "NOD/ShiLtJ", "NZO/HlLtJ",
                 "CAST/EiJ", "PWK/PhJ", "WSB/EiJ")
strains <- sub("/", "_", cc_founders[-2])
n_strains <- length(strains)

library(VariantAnnotation)

library(RSQLite)
db_file <- "cc_variants.sqlite"
db <- dbConnect(SQLite(), dbname=db_file)

dbExecute(db, paste0("ATTACH '", db_file, "' AS NEW"))

cat(" -SNPs\n")
tabfile <- TabixFile(files[1], paste0(files[1], ".tbi"))

db_started <- FALSE
for(thechr in chr) {
    for(left in seq(0, 190, by=10)) {
        cat(thechr, left, "\n")

        # 10 Mbp range
        gr <- GRanges(seqnames=thechr, ranges=IRanges(start=left*1e6, end=(left+10)*1e6-1))

        # grab data
        param <- ScanVcfParam(geno = c("GT", "FI"), samples = strains,
                              which = gr)
        snps <- readVcf(tabfile, genome = "mm10", param = param)
        if(nrow(snps)==0) next

        # drop snps with any quality < 1
        fi <- geno(snps)$FI
        snps <- snps[rowSums(!is.na(fi) & fi==1) == n_strains]

        # drop snps that are all 0/0
        g <- geno(snps)$GT
        snps <- snps[rowSums(is.na(g)) == 0 & rowSums(g=="0/0") < n_strains]
        g <- geno(snps)$GT
        if(nrow(snps)==0) next

        # grab genotypes
        g <- geno(snps)$GT
        # add B6 genotypes (reference) and change column names
        g <- cbind(g[,1,drop=FALSE], C57BL_6J="0/0", g[,-1])
        colnames(g) <- cc_founders

        # alleles
        major <- as.character(ref(snps))
        minor <- CharacterList(alt(snps))
        alleles <- matrix("", nrow=nrow(snps), ncol=4)
        alleles[,1] <- major
        for(i in 2:4) {
            alleles[,i] <- sapply(minor, "[", i-1)
        }

        # numbers of each genotype
        rs <- sapply(c("0/0", "1/1", "2/2", "3/3"),
                     function(a) rowSums(g==a))

        # rows should all sum to 8
        stopifnot(all(rowSums(rs)==8))

        # find the most common allele and swap with major
        for(i in ncol(rs):2) {
            # this allele most common?
            wh <- (rs[,i] > rs[,1] & rowSums(rs <= rs[,i]) == ncol(rs))

            if(any(wh)) {
                # swap alleles
                tmp <- alleles[wh,i]
                alleles[wh,i] <- alleles[wh,1]
                alleles[wh,1] <- tmp

                # swap genotypes
                pat <- paste0(i-1, "/", i-1)
                gg <- g[wh,,drop=FALSE]
                gg[gg==pat] <- "x/x"
                gg[gg=="0/0"] <- pat
                gg[gg=="x/x"] <- "0/0"
                g[wh,] <- gg
            }
        }

        # version with A/C/G/T
        glet <- gnum <- matrix(nrow=nrow(g), ncol=ncol(g))
        dimnames(glet) <- dimnames(gnum) <- dimnames(g)
        for(i in 1:4) {
            pat <- paste0(i-1, "/", i-1)
            for(j in 1:ncol(g)) {
                wh <- (g[,j] == pat)
                glet[wh,j] <- alleles[wh,i]
                gnum[wh,j] <- i
            }
        }

        # NAs in alleles when not seen
        for(i in 1:4) {
            wh <- which(rowSums(gnum==i)==0)
            alleles[wh,i] <- NA
        }

        # alleles as a pattern A|C/G/T
        alleles_char <- paste(alleles[,1],
                              apply(alleles[,-1,drop=FALSE], 1,
                                    function(a) paste(a[!is.na(a)], collapse="/")),
                              sep="|")

        # gnum: turn it into consecutive numbers
        #   (if "2" is missing make 3 = 2)
        for(i in 3:2) {
            wh <- is.na(alleles[,i])
            if(any(wh)) {
                tmp <- gnum[wh,]
                tmp[tmp >= i] <- tmp[tmp >= i] - 1
                gnum[wh,] <- tmp
            }
        }

        # convert to 1/3
        gbin <- gnum
        gbin[gbin > 1] <- 3

        # first row = gene; 2nd row = consequence
        csq <- sapply(info(snps)$CSQ, format_consequence)

        # create full table of info
        snps <- data.frame(snp_id=rownames(g),
                           chr=as.vector(seqnames(snps)),
                           pos=start(snps),
                           alleles=alleles_char,
                           sdp=qtl2::calc_sdp(gbin),
                           ensembl_gene=csq[1,],
                           consequence=csq[2,],
                           gnum,
                           type="snp",
                           stringsAsFactors=FALSE)
        # make sure column names are what we want
        colnames(snps)[8:15] <- c(strains[1], "C57BL_6J", strains[-1])

        dbWriteTable(db, "variants", snps, row.names=FALSE, overwrite=!db_started,
                     append=db_started, field.types=NULL)
        db_started <- TRUE

    }
}

##############################
### indels
##############################
cat(" -InDels\n")
chr <- c(1:19, "X", "Y") # drop MT because not present in indel file
tabfile <- TabixFile(files[2], paste0(files[2], ".tbi"))

for(thechr in chr) {
    for(left in seq(0, 190, by=10)) {
        cat(thechr, left, "\n")

        # 10 Mbp range
        gr <- GRanges(seqnames=thechr, ranges=IRanges(start=left*1e6, end=(left+10)*1e6-1))

        # grab data
        param <- ScanVcfParam(geno = c("GT", "FI"), samples = strains,
                              which = gr)
        indels <- readVcf(tabfile, genome = "mm10", param = param)
        if(nrow(indels)==0) next

        # drop indels with any quality < 1
        fi <- geno(indels)$FI
        indels <- indels[rowSums(!is.na(fi) & fi==1) == n_strains]
        if(nrow(indels)==0) next

        # drop indels that are all 0/0
        g <- geno(indels)$GT
        indels <- indels[rowSums(is.na(g)) == 0 & rowSums(g=="0/0") < n_strains]
        g <- geno(indels)$GT
        if(nrow(indels)==0) next

        # add B6 genotypes (reference) and change column names
        g <- cbind(g[,1,drop=FALSE], C57BL_6J="0/0", g[,-1,drop=FALSE])
        colnames(g) <- cc_founders

        # alleles
        major <- as.character(ref(indels))
        minor <- CharacterList(alt(indels))
        max_minor <- max(sapply(minor, length))
        alleles <- matrix("", nrow=nrow(g), ncol=max_minor+1)
        alleles[,1] <- major
        for(i in 2:(max_minor+1))
            alleles[,i] <- sapply(minor, "[", i-1)

        # numbers of each genotype
        pat <- paste0(0:max_minor, "/", 0:max_minor)
        rs <- sapply(pat, function(a) rowSums(g==a))
        if(!is.matrix(rs)) {
            rs <- matrix(rs, nrow=1)
            dimnames(rs) <- list(rownames(g), pat)
        }

        # rows should all sum to 8
        stopifnot(all(rowSums(rs)==8))

        # find the most common allele and swap with major
        for(i in ncol(rs):2) {
            # this allele most common?
            wh <- (rs[,i] > rs[,1] & rowSums(rs <= rs[,i]) == ncol(rs))

            if(any(wh)) {
                # swap alleles
                tmp <- alleles[wh,i]
                alleles[wh,i] <- alleles[wh,1]
                alleles[wh,1] <- tmp

                # swap genotypes
                pat <- colnames(rs)[i]
                gg <- g[wh,,drop=FALSE]
                gg[gg==pat] <- "x/x"
                gg[gg=="0/0"] <- pat
                gg[gg=="x/x"] <- "0/0"
                g[wh,] <- gg
            }
        }

        # version with alleles
        glet <- gnum <- matrix(nrow=nrow(g), ncol=ncol(g))
        dimnames(glet) <- dimnames(gnum) <- dimnames(g)
        for(i in 1:ncol(rs)) {
            pat <- paste0(i-1, "/", i-1)
            for(j in 1:ncol(g)) {
                wh <- (g[,j] == pat)
                glet[wh,j] <- alleles[wh,i]
                gnum[wh,j] <- i
            }
        }

        # NAs in alleles when not seen
        for(i in 1:ncol(alleles)) {
            wh <- which(rowSums(gnum==i)==0)
            alleles[wh,i] <- NA
        }

        # alleles as a pattern A|C/G/T
        alleles_char <- paste(alleles[,1],
                              apply(alleles[,-1,drop=FALSE], 1,
                                    function(a) paste(a[!is.na(a)], collapse="/")),
                              sep="|")

        # gnum: turn it into consecutive numbers
        #   (if "2" is missing make 3 = 2)
        if(ncol(alleles) >= 3) {
            for(i in 3:2) {
                wh <- is.na(alleles[,i])
                if(any(wh)) {
                    tmp <- gnum[wh,]
                    tmp[tmp >= i] <- tmp[tmp >= i] - 1
                    gnum[wh,] <- tmp
                }
            }
        }

        # convert to 1/3
        gbin <- gnum
        gbin[gbin > 1] <- 3

        # first row = gene; 2nd row = consequence
        csq <- sapply(info(indels)$CSQ, format_consequence)

        # create full table of info
        indels <- data.frame(snp_id=rownames(g),
                             chr=thechr,
                             pos=start(indels),
                             alleles=alleles_char,
                             sdp=qtl2::calc_sdp(gbin),
                             ensembl_gene=csq[1,],
                             consequence=csq[2,],
                             gnum,
                             type="indel",
                             stringsAsFactors=FALSE)
        # make sure column names are what we want
        colnames(indels)[8:15] <- c(strains[1], "C57BL_6J", strains[-1])

        dbWriteTable(db, "variants", indels, row.names=FALSE, overwrite=FALSE,
                     append=TRUE, field.types=NULL)
    }
}


##############################
# structural variants (SVs)
##############################
cat(" -Stuctural variants\n")
tmpfile <- tempfile()
system(paste0("gunzip -c ", files[3], " > ", tmpfile))
svs <- data.table::fread(tmpfile, data.table=FALSE)
unlink(tmpfile)

# pull out genotypes
g <- svs[,colnames(svs) %in% strains]
g <- g[,strains]

# add B6 ref genotype
g <- cbind(g[,1,drop=FALSE], C57BL_6J="0", g[,-1,drop=FALSE], stringsAsFactors=FALSE)

# drop monomorphic ones
n_allele <- apply(g, 1, function(a) length(unique(a)))
svs <- svs[n_allele > 1,]
g <- g[n_allele > 1,]
g[g=="0"] <- "-"

# alleles
alleles <- apply(g, 1, function(a) {
    tab <- table(a)
    result <- names(sort(tab, decreasing=TRUE))
    if(length(result) < 8)
        result <- c(result, rep(NA, 8-length(result)))
    result })
alleles <- t(alleles)

# numeric version
gnum <- matrix(nrow=nrow(g), ncol=ncol(g))
dimnames(gnum) <- dimnames(g)
for(i in 1:ncol(alleles)) {
    for(j in 1:ncol(g)) {
        wh <- (!is.na(alleles[,i]) & g[,j] == alleles[,i])
        gnum[wh,j] <- i
    }
}

# alleles as a pattern A|C/G/T
alleles_char <- paste(alleles[,1],
                      apply(alleles[,-1,drop=FALSE], 1,
                            function(a) paste(a[!is.na(a)], collapse="/")),
                      sep="|")

# convert to 1/3
gbin <- gnum
gbin[gbin > 1] <- 3

# create full table of info
svs <- data.frame(snp_id=paste0("SV_", svs[,"#CHROM"], "_", svs[,"START"], "_", svs[,"END"]),
                  chr=svs[,"#CHROM"],
                  pos=round((svs[,"START"] + svs[,"END"])/2), # average of start and end
                  alleles=alleles_char,
                  sdp=qtl2::calc_sdp(gbin),
                  ensembl_gene=NA,
                  consequence=NA,
                  gnum,
                  type="SV",
                  stringsAsFactors=FALSE)
# make sure column names are what we want
colnames(svs)[8:15] <- c(strains[1], "C57BL_6J", strains[-1])

dbWriteTable(db, "variants", svs, row.names=FALSE, overwrite=FALSE,
             append=TRUE, field.types=NULL)


##############################
### Add description table
##############################

description <- data.frame(description=c("SNPs in Collaborative Cross founders",
                                        "Indels in Collaborative Cross founders",
                                        "SVs in Collaborative Cross founders"),
                          source=c("Mouse Genome Informatics (MGI), Jackson Lab",
                                   "Mouse Genome Informatics (MGI), Jackson Lab",
                                   "Sanger"),
                          url=paste0(site, "/", subdir, "/", files),
                          date_created=rep(as.character(Sys.Date()), 3),
                          date_source=date_source,
                          genome_build=genome_build,
                          stringsAsFactors=FALSE)
dbWriteTable(db, "description", description, append=TRUE)


##############################
### add index
##############################
dbExecute(db, "CREATE INDEX chr_pos ON variants(chr, pos)")
dbDisconnect(db)