Table 5. Genes classified into 16 categories according to the status of age-related expression.
| Category | Fetal stage | 12 weeks | 20 weeks | 30 weeks | Number of genes | Definition |
| 1 | 1 | 1 | 1 | 1 | 6763 | genes expressed from fetal stage to 30 weeks |
| 2 | 0 | 1 | 1 | 1 | 7564 | genes expressed from 12 to 30 weeks |
| 3 | 1 | 0 | 1 | 1 | 49 | |
| 4 | 0 | 0 | 1 | 1 | 3547 | genes expressed from 20 to 30 weeks |
| 5 | 1 | 1 | 0 | 1 | 14 | |
| 6 | 0 | 1 | 0 | 1 | 80 | |
| 7 | 1 | 0 | 0 | 1 | 7 | |
| 8 | 0 | 0 | 0 | 1 | 827 | genes expressed at 30 weeks |
| 9 | 1 | 1 | 1 | 0 | 73 | |
| 10 | 0 | 1 | 1 | 0 | 124 | |
| 11 | 1 | 0 | 1 | 0 | 29 | |
| 12 | 0 | 0 | 1 | 0 | 428 | genes expressed at 20 weeks |
| 13 | 1 | 1 | 0 | 0 | 16 | |
| 14 | 0 | 1 | 0 | 0 | 147 | genes expressed at 12 weeks |
| 15 | 1 | 0 | 0 | 0 | 84 | genes expressed in fetal stage |
| 16 | 0 | 0 | 0 | 0 | 23851 | genes not expressed from fetal stage to 30 weeks |
Depending on the status of expression, all spots on the microarray can be divided into 16 categories. Here, “1” represents an expressed gene and “0” represents an unexpressed gene.