These genes included Transcription Factor 4 (TCF4) (P=3.11×10−5), variation in which has been associated with schizophrenia in genome‐wide association analysis,43 and Interleukin 1 Receptor Accessory Protein‐Like 1 (IL1RAPL1) (P=1.77×10−5), disruption/deletion of which has been identified in individuals with mental retardation and/or autism spectrum disorder (ASD).44, 45, 46, 47, 48, 49, 50 No relationship was found between methylation and estimated CD4+ T‐cell proportion at either the TCF4 site or the IL1RAPL1 site (TCF4: t=−1.22, P=.230; IL1RAPL1: t=1.38, P=.176). This evidence concerns the gene TCF4 and autism spectrum disorder.