Several TIQs, including 1,3-diMeTIQ, have been implicated in various toxic effects, such an inhibition of the tyrosine hydroxylase [22, 23], the tryptophan hydroxylase [24], the catechole-O-methyltransferase [25], and MAO-A and MAO-B [98], as well as potential involvement in pathogenesis of Parkinson’s disease through biotransformation to an N-methylisoquinolinium ion [26–29]. The gene discussed is MAOB; the disease is Parkinson disease.