We estimated heritability of expression phenotypes independently in the CEU and YRI trios by performing midparent-offspring regressions. Of the 47,294 analyzed probes,4,829 and 6,482 (10% and 13%, respectively) demonstrate heritability greater than 0.2 in CEU and YRI, respectively, with an overlap of 958 genes, while 154 CEU genes and 217 YRI had heritability higher than 0.5 with an overlap of just 9 genes. This suggests that even with only 30 trios per population we can detect a substantial number of heritable expression phenotypes, through the low heritability estimates indicate substantial additional non-genetic sources of variation in gene expression.
