Both require that DNA be manipulated in some way.
Answer: <em>Serotonin and Dopamine</em>
Dopamine is a neurotransmitter which is usually associated with attention and learning, and too of it little can be related to several forms of depression.
Also, Serotonin plays a part in the development of mood, appetite and is associated with sleep, whereas; too little of serotonin is related to depression.