COMPENDIUM ON FUNCTIONAL MEDICINE - Flipbook - Page 209
neutralize the increased Alzheimer's risk typically associated with ε4
[27].
Histamine Metabolism Genes (DAO and HNMT)
Function: Two primary enzymes are responsible for breaking down
histamine in the body: Diamine Oxidase (DAO) and Histamine
N-methyltransferase (HNMT). These enzymes work in different parts
of the body to maintain appropriate histamine levels.
DAO (Diamine Oxidase):
● Encoded by the AOC1 gene
● Primary enzyme for breaking down ingested histamine in the
gut
● Active primarily in the digestive tract, kidneys, and placenta
● Responsible for extracellular histamine metabolism
Key DAO Variants:
AOC1 rs10156191
Associated with reduced DAO enzyme activity and decreased
ability to break down dietary histamine, potentially leading to
histamine intolerance symptoms [28].
AOC1 rs1049748
Can affect DAO enzyme production and function, impacting
histamine metabolism.
HNMT (Histamine N-methyltransferase)
● Responsible for breaking down histamine inside cells,
particularly in the central nervous system
● Critical for regulating histamine levels in the brain and
nervous system
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