We previously estimated the heritability of schizophrenia in Sweden to be 0.64 (95% CI 0.617-0.675) using a national pedigree sample of 9.0M individuals,5 and a Danish national pedigree study of 2.6M individuals reported a similar estimate (0.67, 95% CI 0.65-0.71). 5,67Using the 1000 Genomes data with population risk of 0.01, the variance in liability estimate from GCTA accounts for 52% of the heritability (0.33/0.64) and ABPA accounts for 78% of the heritability (0.50/0.64). Imprecision is inherent to these estimates and future work or the use of a twin meta-analytic estimate of the heritability of schizophrenia (0.81, 95% CI 0.73-0.90) 6 could revise these estimates downward. However, despite the use of different assumptions and methods, these estimates converge on a crucial qualitative implication: causal variants tagged by common SNPs make substantial contributions to the risk for schizophrenia.
