Required Sample Size to Detect a 1.5- to 10-fold Difference in mRNA Expression Levels Between Two Groups
| Gene | Mean expression level | No. of individuals in each group | |||
| 1.5-fold difference | 2-fold difference | 5-fold difference | 10-fold difference | ||
| 5-HT-1E | 1.97 | 41 | 15 | 4 | 3 |
| 5-HT-1F | 1.20 | 22 | 9 | 3 | 3 |
| 5-HT-2A | 1.74 | 145 | 51 | 11 | 6 |
| 5-HT-5A | 1.55 | 97 | 34 | 8 | 5 |
| D1 | 1.20 | 94 | 33 | 7 | 5 |
| D5 | 1.65 | 172 | 60 | 12 | 7 |
| CYP26A1 | 1.97 | 155 | 54 | 11 | 6 |
| CYP1A1 | 1.37 | 66 | 24 | 6 | 4 |
| CYP2C8 | 0.95 | 133 | 47 | 10 | 6 |
| CYPD | 2.37 | 49 | 18 | 5 | 3 |
| MAP2 | 1.95 | 62 | 22 | 6 | 4 |
| NSE | 3.23 | 68 | 24 | 6 | 4 |
| GFAP | 2.61 | 221 | 76 | 15 | 8 |
| NOS | 1.85 | 63 | 23 | 6 | 4 |
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We calculated the adjusted means of expression for each of the 27 individuals included in the comparisons among autopsies and for each of the 16 genes analysed. The adjusted mean of expression for each individual is the amount of cDNA copies amplified for each individual, adjusted with the amount of cDNA copies of two covariate reference genes (ACTB and GAPD). ANCOVA analysis is done on the logarithm of the number of copies measured. Mean expression level for each gene is the average for the 27 adjusted means for each gene (logarithm). For the adjusted mean for each individual seehttp://www.genpat.uu.se/psge/psgecastensson.html. The parameters used for the power calculations are the mean and standard deviation of the adjusted means for the 27 individuals (logarithmic data) for each gene. All calculations were done with a power of 95% and a confidence of 95%. The sample sizes shown are the number of individuals required in each of the two groups.
