Not systematically tested in connection with blood levels of 5-HT (Weiss et al., 2005) nor in SERT-oriented models of autism (Quinlan et al., 2020), MAOA and its enzymatic partners however deserve interest, in connection with other concerned agents, including SERT, 5-HT receptors, and TPH2 among a large family of neurotransmission regulators. The gene discussed is TPH2; the disease is autism.