Prevalence of Diamine Oxidase-Encoding Gene Variants and Their Association with Self-Reported Symptoms Among Adults with Adverse Food Reactions in Ganzhou, Eastern China

Background: The prevalence of adverse food reactions (AFRs) in adults appears to be on the rise. Among the various mechanisms underlying AFRs, reduced histamine degradation capacity is one of the crucial pathophysiological bases. Diamine oxidase (DAO) is the key enzyme responsible for degrading exogenous histamine from food, and certain single nucleotide polymorphism (SNP) variants in the amine oxidase copper-containing 1 (AOC1) gene encoding this enzyme are closely associated with reduced DAO activity. Methods: In an epidemiological study of food allergy among adults in Ganzhou, eastern China, we collected oral mucosal samples from 241 cases with self-reported AFRs and 204 healthy controls without a history of AFRs or allergic diseases to analyze three SNP variants associated with DAO deficiency (rs10156191, rs1049793, and rs2052129). Results: The prevalence of genetic DAO deficiency among adults with AFRs was 78.8% (95% CI: 73.1–83.8), with rs1049793 being the most frequent SNP variant. There were no significant differences in the distribution of the three SNP variants and allele variants between AFR cases and controls. Among AFR cases, the proportion of individuals with DAO deficiency who self-reported ≥3 AFR symptoms was significantly higher than that in the normal DAO activity group (24.7% vs. 6.4%; P = 0.006). Furthermore, the number of SNP variants was significantly, albeit weakly, positively correlated with the number of self-reported AFR symptoms (r_s = 0.218, P = 0.001). The proportion of AFR cases presenting with ≥3 symptoms exhibited a stepwise increase with the accumulation of SNP variants. Conclusions: There is a high prevalence of genetic DAO deficiency among adults with AFRs in Ganzhou. AOC1 genotyping is helpful for identifying genetically susceptible individuals who are prone to experiencing multi-system AFR symptoms.