mq.g.diagnostics: Performs molecular markers quality diagnostics.

In kbroman/lmem.gwaser: Linear Mixed Effects Models for Genome-Wide Association Studies

Description

Performs molecular markers quality diagnostic of an object of class cross created by the gwas.cross function, including summary description for marker distribution and coverage, evaluating the map quality, the presence of identical individuals, visualizing marker alleles and missing marker scores for all individuals across the genome, the pairwise number of alleles shared by each pair of individuals, the pairwise recombination fraction among each pair of markers, and a test for segregation distortion for each marker in linkage analysis.

Usage

mq.g.diagnostics(crossobj, I.threshold = 0.1, I.quant = FALSE,
  p.val = 0.01, na.cutoff = 0.1)

Arguments

crossobj	An object of class = cross obtained from the gwas.cross function from this package, or the read.cross function from r/qtl package (Broman and Sen, 2009). This file contains phenotypic means, genotypic marker score, and genetic map.
I.threshold	Threshold for proportion of allelic differences below which individuals are marked as too similar, pairs that differ more than (1-threshold) are marked as exceptioally different. Default is set to 10 per cent (I.threshold = 0.1).
I.quant	Threshold indicating the quantile to identify the most similar individuas. Default is set to FALSE.
p.val	Significance level for the chi-square test for segregation distortion. This function is only used for balanced populations, and is not used in GWAS populations. The default is set to p<0.01. No multiple comparison correction is performed here.
na.cutoff	Proportion of missing data above which individuals and markers are reported . Default is set to 10 per cent (na.cutoff = 0.1).

Details

Performs plots in the work directory.

Value

The following reports are written to mq_reports: 1) mq_g_summary_markers, reports on missing data and segregation distortion.

2) mq_g_problems_markers, reports on duplicate or outlier genotypes.

Additionally, several diagnostic plots are performed:

1) mq_g_markermap_plot, this figure shows the position of all markers across the genome (equivalent R/qtl: plot.map) (Broman and Sen 2009).

2) mq_g_genotype_plot, this figure shows marker alleles for all individuals across thegenome (equivalent to r/qtl: geno.image) (Broman and Sen 2009).

3) mq_g_missinggenotype_plot, this figure highlights missing marker scores for all individuals across the genome (equivalent to r/qtl: plotMissing) (Broman and Sen 2009).

4) mq_g_comparegenotypes_plot, this figure represents the pairwise number of alleles shared by each pair of individuals (equivalent to r/qtl: comparegeno) (Broman and Sen 2009).

6) mq_g_cf_plot, this figure represents the pairwise recombination fraction among each pair of markers (equivalent to r/qtl: plotRF). (Broman and Sen 2009).

7) mq_g_identical_genotypes_plot, this figure is the histogram of the proportion of shared alleles among each pair of individuals.

Note

Performs marker quality daignostics for QTL and GWAS analyses

Author(s)

Lucia Gutierrez, Gaston Quero

References

Broman KW, Sen S (2009) A Guide to QTL Mapping with R/qtl. Springer, NewYork Hayes PM, Liu BH, Knapp SJ, Chen F, Jones B, Blake T, Franckowiak JD, Rasmusson DC, Sorrells M, Ullrich SE, Wesenberg DM, Kleinhofs A (1993) Quantitative trait locus effects and environmental interaction in a sample of North American barley germplasm. Theor Appl Genet 87:392-401

See Also

gwas.cross

Examples

data (QA_geno)
data (QA_map)
data (QA_pheno)

P.data <- QA_pheno
G.data <- QA_geno
map.data <- QA_map

cross.data  <- gwas.cross (P.data, G.data, map.data,
cross='gwas', heterozygotes=FALSE)
summary (cross.data)

#Marker Quality

mq.g.diagnostics (crossobj=cross.data,I.threshold=0.1,
             p.val=0.01,na.cutoff=0.1)

kbroman/lmem.gwaser documentation built on May 30, 2019, 3:10 p.m.