Association of Mitochondrial DNA Copy Number With Atopic Dermatitis in Children

ABSTRACT Background Mitochondrial DNA copy number (mtDNA‐CN), a marker associated with mitochondrial function and cellular health, has been implicated in several chronic inflammatory diseases. Atopic dermatitis is a common chronic inflammatory skin disorder, yet the relationship between mtDNA‐CN and childhood atopic dermatitis remains unclear. This study aimed to investigate the association between mtDNA‐CN and atopic dermatitis in a population‐based cohort of school‐aged children. Methods We included 1329 singleton children (56.4% boys; mean age ± standard deviation: 6.5 ± 0.5 years) from the Longitudinal Investigation of Global Health in Taiwanese Schoolchildren (LIGHTS) cohort. Genomic DNA was extracted from peripheral blood, and mtDNA‐CN was quantified by real‐time quantitative polymerase chain reaction. Multivariable logistic regression models were applied. Results Among the 1329 children, 328 (24.7%) children had physician‐diagnosed atopic dermatitis. Mean mtDNA‐CN was lower in children with atopic dermatitis than in those without (289.62 ± 102.06 vs. 299.47 ± 91.90; p = 0.03). Each one‐unit increase in log‐transformed mtDNA‐CN was associated with 28% lower odds of atopic dermatitis after adjustment for potential confounders (adjusted odds ratio: 0.72; 95% confidence interval: 0.54–0.96). Subgroup analyses showed that this inverse association was more pronounced among children breastfed for ≥ 3 months and those with a birth weight ≥ 2500 g. Conclusion This study provides novel evidence of an inverse association between mtDNA‐CN and atopic dermatitis in children. Further longitudinal and mechanistic studies are warranted to confirm these findings and to evaluate the potential utility of mtDNA‐CN as a biomarker for atopic dermatitis.