HTR1A and sudden infant death syndrome: In our analysis of the 5-HT1A-hippocampal relationship, we focused specifically on hippocampal features shown to have a higher prevalence in SIDS infants compared with controls, namely, focal granule cell bilamination of the DG, clusters of immature cells in the subgranular layer of the DG, and single ectopic granule cells in the molecular layer of the DG (8).