We estimated narrow-sense heritability, h2, for each transcript across the three tissues in all available twin pairs using a variance-component model adjusting for known technical cofactors19. The average h2 estimates of expressed transcripts corresponded to h2adipose=0.26, h2lcl=0.21 andh2skin=0.16 (Fig 1, Supplementary Table 2). The cell-type heterogeneity expected in skin most likely explains the lower estimates in that tissue. We tested how heritability of transcripts compares across tissues and found that around 50% of the top 5000 heritable transcripts in each tissue (corresponding toh2adipose>0.33, h2LCL>0.27 and h2skin>0.22) are in fact heritable across two or more tissues (Supplementary Fig. 1A) with similar results when restricting to transcripts expressed in all three tissues (Supplementary Fig. 1B).
