Investigating the contributions of circadian pathway and insomnia risk genes to autism and sleep disturbances

Sleep disturbance is prevalent in youth with Autism Spectrum Disorder (ASD). Researchers have posited that circadian dysfunction may contribute to sleep problems or exacerbate ASD symptomatology. However, there is limited genetic evidence of this. It is also unclear how insomnia risk genes identified through GWAS in general populations are related to ASD and common sleep problems like insomnia traits in ASD. We investigated the contribution of copy number variants (CNVs) encompassing circadian pathway genes and insomnia risk genes to ASD risk as well as sleep disturbances in children with ASD. We studied 5860 ASD probands and 2092 unaffected siblings from the Simons Simplex Collection (SSC) and MSSNG database, as well as 7509 individuals from two unselected populations (IMAGEN and Generation Scotland). Sleep duration and insomnia symptoms were parent reported for SSC probands. We identified 335 and 616 rare CNVs encompassing circadian and insomnia risk genes respectively. Deletions and duplications with circadian genes were overrepresented in ASD probands compared to siblings and unselected controls. For insomnia-risk genes, deletions (not duplications) were associated with ASD in both cohorts. Results remained significant after adjusting for cognitive ability. CNVs containing circadian pathway and insomnia risk genes showed a stronger association with ASD, compared to CNVs containing other genes. Circadian genes did not influence sleep duration or insomnia traits in ASD. Insomnia risk genes intolerant to haploinsufficiency increased risk for insomnia when duplicated. CNVs encompassing circadian and insomnia risk genes increase ASD liability with little to no observable impacts on sleep disturbances.

Investigating the genetic pathways of insomnia in Autism Spectrum Disorder

BACKGROUND

Sleep problems are common in children with autism spectrum disorder (autism). There is sparse research to date to examine whether insomnia in people with autism is related to autism genetics or insomnia genetics. Moreover, there is a lack of research examining whether circadian-rhythm related genes share potential pathways with autism.

AIMS

To address this research gap, we tested whether polygenic scores of insomnia or autism are related to risk of insomnia in people with autism, and whether the circadian genes are associated with insomnia in people with autism.

METHODS AND PROCEDURES

We tested these questions using the phenotypically and genotypically rich MSSNG dataset (N = 1049) as well as incorporating in the analyses data from the Vanderbilt University Biobank (BioVU) (N = 349).

OUTCOMES AND RESULTS

In our meta-analyzed sample, there was no evidence of associations between the polygenic scores (PGS) for insomnia and a clinical diagnosis of insomnia, or between the PGS of autism and insomnia. We also did not find evidence of a greater burden of rare and disruptive variation in the melatonin and circadian genes in individuals with autism and insomnia compared to individuals with autism without insomnia.

CONCLUSIONS AND IMPLICATIONS

Overall, we did not find evidence for strong effects of genetic scores influencing sleep in people with autism, however, we cannot rule out the possibility that smaller genetic effects may play a role in sleep problems. Our study indicated the need for a larger collection of data on sleep problems and sleep quality among people with autism.

Sleep Problems in Children with ASD and Gene Disrupting Mutations

Sleep difficulties are pervasive in autism spectrum disorder (ASD), yet how sleep problems relate to underlying biological mechanisms such as genetic etiology is unclear, despite recent reports of profound sleep problems in children with ASD-associated de novo likely gene disrupting (dnLGD) mutations, CHD8, DYRK1A, and ADNP. We aimed to inform etiological contributions to ASD and sleep by characterizing sleep problems in individuals with dnLGD mutations. Participants (N = 2886) were families who completed dichotomous questions about sleep problems within a medical history interview for their child with ASD (age 3-28 years). Confirmatory factor analyses compared between those with ASD and a dnLGD mutation and those with idiopathic ASD (i.e., no known genetic event, NON) highlighted four domains (sleep onset, breathing issues, nighttime awakenings, and daytime tiredness) with sleep onset as a strong factor for both groups. Overall, participant predictors indicated that internalizing behavioral problems and lower cognitive scores were related to increased sleep problems. Internalizing problems were also related to increase nighttime awakenings in the dnLGD group. As an exploratory aim, patterns of sleep issues are described for genetic subgroups with unique patterns including more overall sleep issues in ADNP (n = 19), problems falling asleep in CHD8 (n = 22), and increased daytime naps in DYRK1A (n = 23). Implications for considering genetically defined subgroups when approaching sleep problems in children with ASD are discussed.

Autism Spectrum Disorder patients may be susceptible to COVID-19 disease due to deficiency in melatonin

Patients with Autism Spectrum Disorder (ASD) may be particularly prone to develop COVID-19. An unusual extended course of COVID-19 disease illness has been reported in one ASD patient and a group of patients have COVID-19 disease in a neurodevelopmental facility. It has been widely reported that many of those with ASD have substantial sleep disorders with low levels of melatonin and various genetic alterations related to melatonin production have been found. Several lines of evidence point to a substantial role of melatonin in the body's innate defense system including acting as a scavenger, an antioxidant and modulating the immune system. We therefore hypothesize that melatonin deficiency may predispose those ASD patients who have low melatonin output to COVID-19 disease. Potential implications for treatment are discussed.

Dysregulation of Circadian Rhythms in Autism Spectrum Disorders

Background:

The alterations in neurological and neuroendocrine functions observed in the autism spectrum disorder (ASD) involves environmentally dependent dysregulation of neurodevelopment, in interaction with multiple coding gene defects. Disturbed sleep-wake patterns, as well as abnormal melatonin and glucocorticoid secretion, show the relevance of an underlying impairment of the circadian timing system to the behavioral phenotype of ASD. Thus, understanding the mechanisms involved in the circadian dysregulation in ASD could help to identify early biomarkers to improve the diagnosis and therapeutics as well as providing a significant impact on the lifelong prognosis.

Objective:

In this review, we discuss the organization of the circadian timing system and explore the connection between neuroanatomic, molecular, and neuroendocrine responses of ASD and its clinical manifestations. Here we propose interconnections between circadian dysregulation, inflammatory baseline and behavioral changes in ASD. Taking into account, the high relevancy of melatonin in orchestrating both circadian timing and the maintenance of physiological immune quiescence, we raise the hypothesis that melatonin or analogs should be considered as a pharmacological approach to suppress inflammation and circadian misalignment in ASD patients.

Strategy:

This review provides a comprehensive update on the state-of-art of studies related to inflammatory states and ASD with a special focus on the relationship with melatonin and clock genes. The hypothesis raised above was analyzed according to the published data.

Conclusion:

Current evidence supports the existence of associations between ASD to circadian dysregulation, behavior problems, increased inflammatory levels of cytokines, sleep disorders, as well as reduced circadian neuroendocrine responses. Indeed, major effects may be related to a low melatonin rhythm. We propose that maintaining the proper rhythm of the circadian timing system may be helpful to improve the health and to cope with several behavioral changes observed in ASD subjects.

Chronic Fluoride Exposure and the Risk of Autism Spectrum Disorder

The continuous rise of autism spectrum disorder (ASD) prevalent in the past few decades is causing an increase in public health and socioeconomic concern. A consensus suggests the involvement of both genetic and environmental factors in the ASD etiopathogenesis. Fluoride (F) is rarely recognized among the environmental risk factors of ASD, since the neurotoxic effects of F are not generally accepted. Our review aims to provide evidence of F neurotoxicity. We assess the risk of chronic F exposure in the ASD etiopathology and investigate the role of metabolic and mitochondrial dysfunction, oxidative stress and inflammation, immunoexcitotoxicity, and decreased melatonin levels. These symptoms have been observed both after chronic F exposure as well as in ASD. Moreover, we show that F in synergistic interactions with aluminum's free metal cation (Al3+) can reinforce the pathological symptoms of ASD. This reinforcement takes place at concentrations several times lower than when acting alone. A high ASD prevalence has been reported from countries with water fluoridation as well as from endemic fluorosis areas. We suggest focusing the ASD prevention on the reduction of the F and Al3+ burdens from daily life.