正向选择,人类遗传学,群体遗传学
rehh : An R Package吴珂皓 2012年3月29日星期四
正向选择,人类遗传学,群体遗传学
rehh An R package to detect footprints of selection in genome-wide SNPdata from haplotype structure
institut national de la recherche agronomique ,France
正向选择,人类遗传学,群体遗传学
the Brief Introduction of rehh An R packageTo detect the footprint of selection Based on SNP data
Using EHH(Extended Homozygosity Haplotype)Including computation: EHH(Extended Homozygosity Haplotype) iHS(within population) Rsb(across pairs of populations) ….
正向选择,人类遗传学,群体遗传学
About positive selection
positive selection purifying selection
balancing selection
正向选择,人类遗传学,群体遗传学
About EHH EHH: Extended Homozygosity HaplotypePresented firstly by Pardis C. Sabeti the probability that two randomly chosen haplotypes carrying the
candidate core haplotype are homozygous for the entire intervalspanning the core region to a given locus (Sabeti P.C et al. 2002).
Sabeti PC, et al. Detecting recent positive selection in the human genome from haplotype structure.
正向选择,人类遗传学,群体遗传学
About EHH12 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 0
A
G
C
T
12 3 4 5 6 7 8 9
正向选择,人类遗传学,群体遗传学
正向选择,人类遗传学,群体遗传学
About REHHRelative EHH is the ratio of the EHH on the tested core haplotype compared with the EHH of the grouped set of core haplotypes at the region not including the core haplotype tested.
正向选择,人类遗传学,群体遗传学
About iHH integrated EHH (iHH) : summed over both directions away from the coreSNP
The expectation and standard deviation of ln(iHHA/iHHD) are estimated from the empirical distribution at SNPs whose derived allele frequency p matches the frequency at the core SNP.
正向选择,人类遗传学,群体遗传学
About EHHS EHHS: decay of EHH of an individual SNP site
正向选择,人类遗传学,群体遗传学
About iES
正向选择,人类遗传学,群体遗传学
About Rsb
正向选择,人类遗传学,群体遗传学
About Input File
SNP information file
SNP rs6718902 ……..
chromosome 2
base position 191838204
ancestral allele 1
derived allele 2
genotype data file
name 1 2 ……….
SNP1 1 1
SNP2 2 2
SNP3 2 1
SNP4 1 1
正向选择,人类遗传学,群体遗传学
About Input File
data2haplohh()CHI<-data2haplohh("CHI.hap","CHI.inp",min_maf=0,min_perc_geno.hap=100,min_perc_geno.snp=100,=NA,popsel=NA,recode.allele=FALSE)
parametero
min_maf
SNPs displaying a MAF<min_maf will be discard
o
min_perc_geno.hapmin_perc_geno.snp popsel recode.allele
Haplotypes with less than min_perc_geno.hapSNPs genotyped on less than min_perc_geno.snp
percent SNPs genotyped will be discardo
percent haplotypes will be discardo o o
name of chromosome code of population considered if true ,alleles will be recoded according to the map file
正向选择,人类遗传学,群体遗传学
About calculation calc_ehh()calc_ehhs()
EHH and iHH computationEHHS and iES computation
正向选择,人类遗传学,群体遗传学
About calculation scan_hh()encode in C 140 individuals , 1424 SNPs 3.2GHz 3.3second
scan_hh(CHI,limhaplo=2,limehh=0.05,limehhs=0.05)o o o
limhaplo limehh
minimal number of haplotypes limit below which EHH stops to be evaluated
limehhs
limit below which EHHS stops to be evaluated
正向选择,人类遗传学,群体遗传学
About calculation ies2rsb(hh_pop1,hh_pop2,popname1=NA,popname2=NA,method="b
ilateral")Compute Rsb ( standardized ratio of iES from two populations ) hh_pop1o
a matrix with nsnps rows and six columns – – – – – – chromosome name position frequency of ancestral alleles iHH of ancestral alleles iHH for the derived allele iES
popname1 method
name of population bilateral or unilateral
正向选择,人类遗传学,群体遗传学
About calculation ihh2ihs(res_ihh,freqbin=0.025,minmaf=0.05)Compute his ( standardized iHH)o
res_ihh
a matrix with nsnps rows and six columns – chromosome name – position – frequency of ancestral alleles – iHH of ancestral alleles – iHH for the derived allele – iES
o
freqbin Size of the bin to standardize log(iHH1/iHH2) according to the underlying Derived
Allele frequency. Allele frequency bins vary from minmaf to 1-minmaf per step of size freqbin. Iffreqbin is set to 0 (e.g. in the case of a large number of SNPs and few haplotypes), standardization is performed considering each observed frequency as a frequency class.o
minmaf SNPs with a MAF lower than minmaf will be discard
正向选择,人类遗传学,群体遗传学
About calculation distribplot(data,col=c("blue","red"),main="his distribution",xlab="iHS")
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