TABLE 1.

Potential Explanations for the modest capture of Heritability by GWAS

A large number of common variants with low magnitude of effect – polygenic inheritance Rare variants with large effects – single gene or oligogenic inheritance Structural variants – rare variants with high mutation rates Interactions between alleles at homologous loci (dominance) and between alleles at non-homologous loci (epistasis) Parent of origin effects Epigenetics effects Underestimation of the effect of shared environment among relatives leading to inflated estimate of heritability.