PER2 and attention deficit-hyperactivity disorder: Circular–circular correlation analyses (supplementary Table S8) revealed several significant associations between the phase angles of circadian genes and WNT signaling/stress-related genes for the ADHD group (CLOCK–CTNNB1, ρ = 2.17, p = 0.029; CRY1–SIRT1, ρ = 3.12, p = 0.002; PER2‒SIRT1, ρ = 2.12, p = 0.034; PER2–FOXO1, ρ = 2.73, p = 0.006; PER3‒FOXO1, ρ = 2.09, p = 0.036; PER1–SIRT1, ρ = − 2.31, p = 0.021) and the control group (CRY1–FOXO1, ρ = − 2.15, p = 0.031).