rs10156191 — AOC1 (DAO) Thr16Met

DAO Structural Variant - When the Enzyme Itself Is Altered

While rs2052129 affects how much DAO enzyme your body makes, the Thr16Met ¹¹ Threonine to methionine at position 16 variant (rs10156191) changes the actual structure of the enzyme protein. This is a missense mutation ²² A missense mutation changes one amino acid to another in the resulting protein that substitutes threonine with methionine at position 16, potentially altering the enzyme's ability to bind and degrade histamine.

The Mechanism

The amino acid change at position 16 occurs in a region of the protein that influences its folding and copper-binding ability. DAO is a copper-dependent enzyme ³³ DAO requires copper ions at its active site to catalyze the oxidation of histamine, and structural changes near the active site can reduce catalytic efficiency. The T allele produces an enzyme that is less effective at breaking down histamine, even when produced in normal quantities. Ayuso et al.⁴⁴ Ayuso et al.
Ayuso P et al. Genetic variability of human diamine oxidase. Pharmacogenet Genomics, 2007 found that carriers of the variant allele had reduced serum DAO activity compared to non-carriers.

Clinical Significance

This variant is frequently studied alongside other AOC1 variants to determine overall DAO haplotype status. Research by Maintz et al.⁵⁵ Maintz et al.
Maintz L & Novak N. Histamine and Histamine Intolerance. Am J Clin Nutr, 2007 and others has shown that carrying multiple DAO risk variants (across rs2052129, rs10156191, and rs1049793) has an additive effect on reducing enzyme activity. An individual who is heterozygous ⁶⁶ Heterozygous means carrying one normal and one variant copy of a gene at all three positions may have more impaired DAO function than someone who is homozygous at just one. The variant is notably more common in African populations (T allele ~51%) compared to East Asian populations (~11%).

What This Means for You

If you carry the T allele here, evaluate your overall DAO status by considering all three AOC1 variants together. Mild impairment at one position can often be compensated, but compound impairment across multiple variants may tip the balance toward clinically meaningful histamine intolerance. Practical dietary strategies remain the same: fresh foods, low-histamine choices, and DAO supplements with meals if needed.