TPH2 and sudden infant death syndrome: Our laboratory has identified multiple abnormalities in SIDS, including brainstem (medullary) abnormalities in indices of serotonin (5-hydroxytryptamine, 5-HT) neurotransmission [e.g., 5-HT1A receptor binding, 5-HT levels, tryptophan hydroxylase 2 (TPH-2) levels]6–9 and the 14–3–3 family of signaling proteins which have been shown to regulate many functions in brain development, including 5-HT synthesis10,11.