V(y)=V=Aσg2+Iσe2 where σg2 is additive genetic variance tagged by the SNPs, σe2 is error variance, A is the realized similarity relationship matrix estimated from SNP data19 and I is an identity matrix. All variances were estimated on the observed case-control scale and were transformed to the liability scale, which requires specification of the disorder risk K to estimate hSNP2. Risk to first-degree relatives was calculated from K and hSNP2 on the basis of the liability threshold model62.
