MuTHER reported mean h2 in expressed genes of 0.16 (skin), 0.21 (LCLs), and 0.26 (adipose), with >20% of expressed genes displaying h2 > 0.3.8 Our study, although much larger, produced lower values of 0.14 and 12.3%. Our average h2 should be unbiased, as we allowed for negative estimates (even if true h2≥0) whereas variance-component methods8 can produce bias by forcing estimates to be nonnegative, and sampling variability further complicates the view.
