The tertiary stage of arsenic toxicity in human causes the neuropathy (5, 6) which may alter the activities or actions of central and peripheral nervous systems due to the changes in the activities of all or some of the neurotransmitters-mediating enzymes, like, Aromatic L-Amino Acid decarboxylase (AADC), DBH and PNMT, and their neurotransmitter-products (dopamine, serotonin, norepinephrine and epinephrine). The gene discussed is DDC; the disease is neuropathy.