Gene type | CpG island state | Total genes considered | Expressed genes | Fraction | Fraction ratio |
|---|
Embryo | CGI+ | 933 | 365 | 39% | 2.8 |
| Â | CGI- | 1007 | 139 | 14% | Â |
Adult-specific | CGI+ | 29 | 8 | 29% | 4 |
| Â | CGI- | 180 | 12 | 7% | Â |
- We determined the fraction of genes with (39%) and without (14%) start CpG islands that are expressed in the early embryo. A gene is 2.8 (= 0.39/0.14) times more likely to be expressed in the early embryo if it has a start CpG island. If we then consider genes that go on to be specific in the adult, we find the ratio of CGI+/CGI- genes is now 4 = 0.28/0.07. The differences in rates between CpG island status within each stage are significant (P < 0.0005; binomial). Of the between-stage comparisons, only the CGI- adult-specific/embryo change is significant (P = 0.0009; hypergeometric).
