Genotype Imputation Given Inheritance
GIGI is a computer program to impute missing
genotypes on pedigrees. Our
approach handles large pedigrees by using a Markov Chain Monte
Carlo-based program to infer inheritance vectors. Our approach
has 2 steps:
1. use the program gl_auto from the MORGAN package to infer inference vectors using genotypes from informative framework markers
2. use GIGI to impute missing genotypes
ReferenceCheung, CYK., Thompson, E.A., Wijsman, E.M. (2013). GIGI: An approach to effective imputation of dense genotypes on large pedigrees. American Journal of Human Genetics 92:504-516 [link]
Older version: v1.05
Older version: v1.03
Older version: v1.02
This program depends on gl_auto output from MORGAN version 3.2. You can download MORGAN version 3.2 and find links to a user tutorial here.
We no longer support MORGAN version 3.1.1, but the gl_auto version 3.1.1 tutorial is available here for users who have files in this older format.
Blue EM, Cheung CYK, Glazner CG, Conomos MP, Lewis SM,
Sverdlov S, Thornton T, Wijsman EM (2014) Identity-by-descent graphs
offer a flexible framework for imputation and both linkage and
association analyses. BMC Proceedings 8(Suppl 1):S19.
- explores the idea of combining information from pedigree using GIGI and information from Linkage Disequibilirum using BEAGLE to impute genotypes.
- For imputation of rare alleles, the use of GIGI alone perfoms similarly to the combined approach, because effective imputation of rare alleles mainly comes from the pedigree with Inheritance Vectors.
- For imputation of common variants, our results suggest that combining BEAGLE with GIGI further improves imputation.
- gives support to the idea that the use of estimated probabilities to compute "dosage" to test for association between phenotype and SNPs may give higher power than the use of imputed results from genotype calls because "dosage" captures the uncertainties in imputated results.
GIGI is for imputing genotypes on pedigrees with known
pedigree structure. If the goal is to impute genotypes on
unrelated individuals, consider using a population-based
genotype imputation program (eg. BEAGLE) instead.
last updated: February 2, 2015