IL1B (non-Chr21) and S100B (Chr21) are involved in astroglial cell proliferation, and activation and interactions may be responsible for abnormally prominent and tortuous neural process formation, causing ID in DS (Griffin et al., 1989; Griffin et al., 1998) (Figures 4B, 5B, 6 and Table 1). The gene discussed is IL1B; the disease is Dravet syndrome.