HTR1B and attention deficit-hyperactivity disorder: Subjects: male children (n = 117) with CU traits, aged 3–16 years. Subjects were grouped by CU traits (see text). Comorbidity: ODD/CD n = 57), ADHD (n = 33), anxiety/depression (n = 11), ASD (n = 15). Diagnostic: DSM-IV, DISCAP, APSD, SDQ, QFE. Methods: DNA sequencing of HTR1B SNP rs11568817genotype by PCR and mass spectrometry analysis. Selected methylation quantification by quantitative mass spectroscopy of three CpG rich regions surrounding the SNP (19 CpG).