Seminar Series in Quantitative Life Sciences and Medicine

"Ancestry attracts, but love is blind: Evaluation of structured mating"

Josee Dupuis (Boston University, School of Public Health)
Tuesday October 23, 12-1pm
McIntyre Building, Room 1027

Abstract: Genetic similarity of spouses can reflect factors influencing mate choice, such as physical/behavioral characteristics, and social customs. Spouse correlations for both genetic ancestry and measured traits may impact genotype distributions (Hardy Weinberg and linkage equilibrium), and therefore genetic association studies. We evaluate white spouse-pairs from the Framingham Heart Study original and offspring cohorts to explore spousal genetic similarity and its consequences. Genetic ancestry was measured using principal components (PCs) of the genome-wide association genotypes, with the first PC (PC1) delineating clines of Northern/Western to Southern European ancestry and the second (PC2) delineating clines Ashkenazi Jewish ancestry. In the original (older) cohort, there was a striking positive correlation between the spouses in PC1 (correlation coefficient (r) = 0.73, P = 3x10-22) and also for PC2 (r = 0.80, P = 7x10-29). In the offspring cohort, the spouse correlations were lower but still highly significant for PC1 (r = 0.38, P = 7x10-28) and for PC2 (r = 0.45, P = 2x10-39). We observed significant Hardy-Weinberg disequilibrium for single nucleotide polymorphisms (SNPs) with high weights for PC1 and PC2 across 3 generations, decreasing with time, consistent with reduced ancestral endogamy over generations. Spouse genetic similarity could be fully attributed to ancestral assortative mating. We conclude with a discussion of the implication of these findings on studies of heritability and genome-wide association studies.