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Updated: Apr 26, 2026

Assessing Differences in Sperm Competitive Ability in Drosophila
Published on: August 22, 2013
Single-nucleotide polymorphism data support the general unrelatedness of the males in the agricultural health study
John R Jack1, Alison A Motsinger-Reif2, Stella Koutros3
1Department of Statistics, Bioinformatics Research Center, Center for Human Health and the Environment, Center for Comparative Medicine and Translational Research, North Carolina State University, Raleigh, North Carolina. jrjack@ncsu.edu.
Background:
Farming is often a family and multigenerational business. Relatedness among farmers could bias gene-environment interaction analysis. To evaluate the potential relatedness of farmers, we used data from a nested case-control study of prostate cancer conducted in the Agricultural Health Study (AHS), a prospective study of farmers in Iowa and North Carolina.
Methods:
We analyzed the genetic data for 25,009 SNPs (single-nucleotide polymorphisms) from 2,220 White participants to test for cryptic relatedness among these farmers. We used two software packages: (i) PLINK, to calculate inbreeding coefficients and identity-by-descent (IBD) statistics and (ii) EIGENSOFT, to perform a principal component analysis on the genetic data.
Results:
Inbreeding coefficients estimates and IBD statistics show that the subjects are overwhelmingly unrelated, with little potential for cryptic relatedness in these data.
Conclusions:
Our analysis rejects the hypothesis that individuals in the case-control study exhibit cryptic relatedness.
Impact:
These findings are important for all subsequent analyses of gene-environment interactions in the AHS.
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