Vitamin A status is associated with sleep, clock genes, and symptoms in children with autism spectrum disorder.

Background: Vitamin A signals through retinoic acid receptors and may influence neurodevelopment and the expression of clock genes. However, the biological pathway linking vitamin A status to sleep disturbance in ASD remains insufficiently defined. This study aimed to examine associations between vitamin A status and sleep problems, core symptoms, and clock genes in children with ASD, and to explore the mechanistic role of RARβ in regulating core clock genes. Methods: This observational study included 361 children with ASD. Clinical symptoms were assessed using the Children's Sleep Habits Questionnaire (CSHQ); the Childhood Autism Rating Scale (CARS) and the Social Responsiveness Scale (SRS). Peripheral blood mononuclear cell (PBMC) mRNA levels of RARβ and clock genes (BMAL1 and CLOCK) were quantified by qPCR. RARβ expression was knocked down in mice by stereotaxic injection of adeno-associated virus. Results: Children with lower vitamin A levels exhibited more severe sleep problems and autistic symptoms. Vitamin A levels showed a weak positive correlation with the expression of RARβ and BMAL1. RARβ knockdown reduced the expression of RARβ and clock genes in mouse brain tissue. Chromatin immunoprecipitation quantitative PCR (ChIP-qPCR) confirmed RARβ occupancy at a predicted CLOCK regulatory region. Conclusion: This study provided evidence that vitamin A status was linked to sleep problems, symptom severity, and expression of clock genes in the morning in ASD. We also found that RARβ signaling may regulate the expression of clock genes. This finding provides new insights into the mechanisms underlying sleep disturbances in ASD, but further functional studies are needed to confirm these findings.