Impact of AOC1 and HNMT Variants on the Therapeutic Outcomes of a Histamine Reducing Diet in Autism Spectrum Disorder.

This study aimed to investigate the effects of a histamine-reducing diet on five developmental domains in autism spectrum disorder subjects and the impact of variants in the AOC1 and HNMT genes on the therapeutic outcomes. Four genetic variants (rs2052129, rs10156191, rs1049742, and rs11558538) in AOC1 and HNMT were genotyped in 400 Bulgarian children with ASD. Genotype and allele frequencies were compared to control data from the GnomAD database. Further analysis was conducted on 91 ASD subjects with elevated histamine who followed the histamine-reducing diet. Significant improvements were observed across all developmental domains measured by the DP-3 test, including physical, adaptive behavior, social-emotional, cognitive, and communication skills. Paired samples T-tests indicated statistically significant increases in all categories (p < 0.001), with physical scores increasing from 82.29 to 89.18, adaptive behavior from 72.68 to 81.35, social-emotional from 71.43 to 80.22, cognitive from 69.33 to 78.66, and communication from 67.36 to 77.54. Minor allele carriers exhibited lower mean improvements across each of the five developmental parameters compared to wild-type carriers, with mean reductions of 0.90 for rs2052129, 0.70 for rs10156191, 2.07 for rs1049742, and 1.94 for rs11558538. These findings highlight the potential role of histamine regulation in autism spectrum disorder, the impact of variants in the AOC1 and HNMT genes on the therapeutic outcome and suggest dietary management as a viable intervention to improve developmental outcomes.