Pearson’s correlation revealed a highly significant association between age and transcript expression for both HDAC1 : F(1,316) = 11.46, r = −0.187, p = 8 × 10 –4 and HDAC2 : F(1, 305) = 62.17, r = −0.411, p < 10 –13 .
The covariates applied and additional percent variance described by each were: RNA integrity, RIN (6.7%); race (6.9%); pH (5.1%); smoking status (2.2%); age at death (4.4%); and sex (1.4%). Correction for transcript measurements collected in two data sets was also applied (6.9% variance), as well as a conservative correction for postmortem interval, which revealed marginal significance ( p = 0.10) within samples from the BP group alone.