The meta-regression analysis showed that the mean age (p = 0.0273) and proportion of males (p = 0.0057) among AD subjects (Fig. 4A, B), but not publication year (p = 0.5313) or sample size (p = 0.1819), had a significant impact on heterogeneity in the meta-analysis of TSLP levels. The gene discussed is TSLP; the disease is Alzheimer disease.