The study showed that in children with severe epilepsy, numerous PSA-NCAM+ immature neurons exist in the SGZ and GCL of the hippocampus of children younger than 2 years of age, but such neurons decrease in number by 6–8 years of age, and are undetectable in older children (>8 years of age) (Mathern et al., 1994, 2002). The gene discussed is NCAM1; the disease is epilepsy.