In the youngest SIDS infants (“Early”), low 5-HT1A binding appeared infrequently in the 5-HT source nuclei (ROb/RMg, GC, PGCL, IRZ) but frequently in the 2 target nuclei: DMX (71% of SIDS infants) and HG (55% of SIDS infants). The gene discussed is HTR1A; the disease is sudden infant death syndrome.