How does AADC deficiency affect the brains neurotransmitters?

Neurotransmitters are a sensitive chain of signals along pathways in the brain which ultimately lead to a correct instruction for bodily function. In AADC deficiency these sensitive chains of signals fail to complete.

L-Dopa and 5-Hydoxytryptophan need correct AADC function to convert them to the active neurotransmitters; Dopamine and Serotonin respectively.

Lack of Dopamine and Serotonin means the brain is also deficient of other neurotransmitters such as:

Norepinephrine (noradrenaline)
Epinephrine (adrenaline)
Melatonin

In addition to the lack of essential neurotransmitters, excessive quantities of the precursers L-dopa and 5 Hydroxytryptophan accumulate in brain and other body tissues. It is still unknown as to how exactly this may affect a child with AADC deficiency.

What neurotransmitters and pathways are implicated in AADC deficiency?

In AADC deficiency pathways associated with the following are affected in some way and to varying degrees from child to child:

L-Dopa - (excess of)
5 Hydroxytrptophan - (excess of)
Dopamine - (lack of)
Norepinephrine - (lack of)
Epinephrine - (lack of)
Serotonin - (lack of)
Melatonin - (lack of)
S-adenosylmethionine (lack of)
5-methyltetrahydrofolate (lack of)

It’s very hard to quantify exactly what and how many other neurotransmitters and pathways are implicated in AADC deficiency, as there is still much more research needed to understand this disease.