Convergence of genes and cellular pathways dysregulated in autism spectrum disorders

Rare copy-number variation (CNV) is an important source of risk for autism spectrum disorders (ASDs). We analyzed 2,446 ASD-affected families and confirmed an excess of genic deletions and duplications in affected versus control groups (1.41-fold, p = 1.0 × 10⁻⁵) and an increase in affected subjects carrying exonic pathogenic CNVs overlapping known loci associated with dominant or X-linked ASD and intellectual disability (odds ratio = 12.62, p = 2.7 × 10⁻¹⁵, ∼3% of ASD subjects). Pathogenic CNVs, often showing variable expressivity, included rare de novo and inherited events at 36 loci, implicating ASD-associated genes (CHD2, HDAC4, and GDI1) previously linked to other neurodevelopmental disorders, as well as other genes such as SETD5, MIR137, and HDAC9. Consistent with hypothesized gender-specific modulators, females with ASD were more likely to have highly penetrant CNVs (p = 0.017) and were also overrepresented among subjects with fragile X syndrome protein targets (p = 0.02). Genes affected by de novo CNVs and/or loss-of-function single-nucleotide variants converged on networks related to neuronal signaling and development, synapse function, and chromatin regulation.

Melatonin for sleep in children with autism: a controlled trial examining dose, tolerability, and outcomes

Supplemental melatonin has shown promise in treating sleep onset insomnia in children with autism spectrum disorders (ASD). Twenty-four children, free of psychotropic medications, completed an open-label dose-escalation study to assess dose-response, tolerability, safety, feasibility of collecting actigraphy data, and ability of outcome measures to detect change during a 14-week intervention. Supplemental melatonin improved sleep latency, as measured by actigraphy, in most children at 1 or 3 mg dosages. It was effective in week 1 of treatment, maintained effects over several months, was well tolerated and safe, and showed improvement in sleep, behavior, and parenting stress. Our findings contribute to the growing literature on supplemental melatonin for insomnia in ASD and inform planning for a large randomized trial in this population.

Gastrointestinal dysfunction in autism: parental report, clinical evaluation, and associated factors

The objectives of this study were to characterize gastrointestinal dysfunction (GID) in autism spectrum disorder (ASD), to examine parental reports of GID relative to evaluations by pediatric gastroenterologists, and to explore factors associated with GID in ASD. One hundred twenty-one children were recruited into three groups: co-occurring ASD and GID, ASD without GID, and GID without ASD. A pediatric gastroenterologist evaluated both GID groups. Parents in all three groups completed questionnaires about their child's behavior and GI symptoms, and a dietary journal. Functional constipation was the most common type of GID in children with ASD (85.0%). Parental report of any GID was highly concordant with a clinical diagnosis of any GID (92.1%). Presence of GID in children with ASD was not associated with distinct dietary habits or medication status. Odds of constipation were associated with younger age, increased social impairment, and lack of expressive language (adjusted odds ratio in nonverbal children: 11.98, 95% confidence interval 2.54-56.57). This study validates parental concerns for GID in children with ASD, as parents were sensitive to the existence, although not necessarily the nature, of GID. The strong association between constipation and language impairment highlights the need for vigilance by health-care providers to detect and treat GID in children with ASD. Medications and diet, commonly thought to contribute to GID in ASD, were not associated with GID status. These findings are consistent with a hypothesis that GID in ASD represents pleiotropic expression of genetic risk factors.

Recurrent reciprocal 16p11.2 rearrangements associated with global developmental delay, behavioural problems, dysmorphism, epilepsy, and abnormal head size

BACKGROUND

Deletion and the reciprocal duplication in 16p11.2 were recently associated with autism and developmental delay.

METHOD

We indentified 27 deletions and 18 duplications of 16p11.2 were identified in 0.6% of all samples submitted for clinical array-CGH (comparative genomic hybridisation) analysis. Detailed molecular and phenotypic characterisations were performed on 17 deletion subjects and ten subjects with the duplication.

RESULTS

The most common clinical manifestations in 17 deletion and 10 duplication subjects were speech/language delay and cognitive impairment. Other phenotypes in the deletion patients included motor delay (50%), seizures ( approximately 40%), behavioural problems ( approximately 40%), congenital anomalies ( approximately 30%), and autism ( approximately 20%). The phenotypes among duplication patients included motor delay (6/10), behavioural problems (especially attention deficit hyperactivity disorder (ADHD)) (6/10), congenital anomalies (5/10), and seizures (3/10). Patients with the 16p11.2 deletion had statistically significant macrocephaly (p<0.0017) and 6 of the 10 patients with the duplication had microcephaly. One subject with the deletion was asymptomatic and another with the duplication had a normal cognitive and behavioural phenotype. Genomic analyses revealed additional complexity to the 16p11.2 region with mechanistic implications. The chromosomal rearrangement was de novo in all but 2 of the 10 deletion cases in which parental studies were available. Additionally, 2 de novo cases were apparently mosaic for the deletion in the analysed blood sample. Three de novo and 2 inherited cases were observed in the 5 of 10 duplication patients where data were available.

CONCLUSIONS

Recurrent reciprocal 16p11.2 deletion and duplication are characterised by a spectrum of primarily neurocognitive phenotypes that are subject to incomplete penetrance and variable expressivity. The autism and macrocephaly observed with deletion and ADHD and microcephaly seen in duplication patients support a diametric model of autism spectrum and psychotic spectrum behavioural phenotypes in genomic sister disorders.

Parent-based sleep education workshops in autism

To determine if parents can successfully teach their children with autism spectrum disorders to become better sleepers, we piloted small group parent education workshops focused on behavioral sleep strategies. Workshops consisted of three 2-hour sessions conducted over consecutive weeks by 2 physicians. Curricula included establishing effective daytime and nighttime habits, initiating a bedtime routine, and optimizing parental interactions at bedtime and during night wakings. Baseline and treatment questionnaires and actigraphy were analyzed in 20 children, ages 3 to 10 years. Improvements after treatment were seen in the total scale and several insomnia-related subscales of the Children's Sleep Habits Questionnaire. Actigraphy documented reduced sleep latency in children presenting with sleep onset delay. Improvements were also noted in measures of sleep habits and daytime behavior. Brief parent-based behavioral sleep workshops in children with autism spectrum disorders appear effective in improving subjective and objective measures of sleep, sleep habits, and daytime behavior.

A sleep habits questionnaire for children with autism spectrum disorders

Sleep difficulties in children with autism spectrum disorders are common, with poor sleep hygiene a contributing factor. We developed the Family Inventory of Sleep Habits to measure sleep hygiene in this population. Its validity and reliability in 2 groups of children aged 4 to 10 years, those with a clinical diagnosis of autism spectrum disorders, and those who are typically developing are described. In both groups, total and modified (reflecting insomnia subscales) scores on the Children's Sleep Habits Questionnaire showed significant negative correlations with the total score. The Peabody Picture Vocabulary Test-III was significantly correlated with total score in the autism spectrum group but not in the typically developing group. Age and socioeconomic status were not correlated with total score in either group. This preliminary work suggests that the Family Inventory of Sleep Habits is a valid and reliable measure of sleep hygiene in autism spectrum disorders.

Melatonin for insomnia in children with autism spectrum disorders

We describe our experience in using melatonin to treat insomnia, a common sleep concern, in children with autism spectrum disorders. One hundred seven children (2-18 years of age) with a confirmed diagnosis of autism spectrum disorders who received melatonin were identified by reviewing the electronic medical records of a single pediatrician. All parents were counseled on sleep hygiene techniques. Clinical response to melatonin, based on parental report, was categorized as (1) sleep no longer a concern, (2) improved sleep but continued parental concerns, (3) sleep continues to be a major concern, and (4) worsened sleep. The melatonin dose varied from 0.75 to 6 mg. After initiation of melatonin, parents of 27 children (25%) no longer reported sleep concerns at follow-up visits. Parents of 64 children (60%) reported improved sleep, although continued to have concerns regarding sleep. Parents of 14 children (13%) continued to report sleep problems as a major concern, with only 1 child having worse sleep after starting melatonin (1%), and 1 child having undetermined response (1%). Only 3 children had mild side-effects after starting melatonin, which included morning sleepiness and increased enuresis. There was no reported increase in seizures after starting melatonin in children with pre-existing epilepsy and no new-onset seizures. The majority of children were taking psychotropic medications. Melatonin appears to be a safe and well-tolerated treatment for insomnia in children with autism spectrum disorders. Controlled trials to determine efficacy appear warranted.

Characterizing sleep in children with autism spectrum disorders: a multidimensional approach

STUDY OBJECTIVES

To relate parentally reported sleep concerns in autism spectrum disorders (ASD) to polysomnographic (PSG) findings and measures of daytime behavior and autism symptomatology.

DESIGN

Cross-sectional study involving validated questionnaires, sleep histories and diaries, 2 nights of PSG, and the Autism Diagnostic Observation Schedule (ADOS).

SETTING

Vanderbilt University General Clinical Research Center Sleep Core.

PARTICIPANTS

21 children with ASD and 10 typically developing (TD) children, aged 4-10 years. Children were free of psychotropic medications, with no history of mental retardation or epileptic seizures.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Children with ASD were defined as "good sleepers" (10 children) and "poor sleepers" (11 children) on the basis of parental report; the age-comparable TD children were all reported by their parents to be good sleepers. Poor sleepers with ASD showed prolonged sleep latency and decreased sleep efficiency on night 1 of PSG and differed on insomnia-related subscales of the Children's Sleep Habits Questionnaire (CSHQ; increased sleep onset delay and decreased sleep duration). The good sleepers with ASD did not differ from the TD children in sleep architecture or on CSHQ domains. As compared with ASD good sleepers, the ASD poor sleepers also had higher scores related to affective problems on the Child Behavior Checklist and more problems with reciprocal social interaction on the ADOS.

CONCLUSIONS

Parentally reported sleep concerns of insomnia in children with ASD are substantiated by validated sleep questionnaires and by PSG. Furthermore, good sleepers with ASD showed fewer affective problems and better social interactions than ASD poor sleepers.

Impact of treating sleep apnea in a child with autism spectrum disorder

Sleep disorders can affect daytime functioning in a variety of neurologic conditions, including autism spectrum disorder. This report describes improvements in sleep, social communication, attention, repetitive behaviors, and hypersensitivity after adenotonsillectomy for obstructive sleep apnea in a 5-year-old female with an autism spectrum disorder. Improvements were documented via pre- and postsurgical measures of parent report, polysomnography, validated sleep and behavior scales, and the Autism Diagnostic Observation Schedule. Identification and treatment of sleep disorders, including obstructive sleep apnea, may improve daytime behavior in children with autism spectrum disorders.

Positive cooperativity of ryanodine binding to the calcium release channel of sarcoplasmic reticulum from heart and skeletal muscle

Ryanodine is a specific ligand for the calcium release channel which mediates calcium release in excitation-contraction coupling in muscle. In this study, ryanodine binding in sarcoplasmic reticulum from heart muscle and skeletal muscle is further compared and correlated with function. The new findings include the following: (1) Two types of binding, high affinity (KD1 approximately 5-10 nM) and low affinity (KD2 approximately 3 microM), can now be discerned for the skeletal muscle receptor. KD1 is approximately the same as and KD2 of similar magnitude to that previously reported for heart. (2) The dissociation rates for the high-affinity binding have been directly measured for both heart and skeletal muscle (t1/2 approximately 30-40 min). These rates are more rapid than previously reported (t1/2 approximately 14 h). (3) KD1's obtained from the ratio of the dissociation and association rate constants agree with the dissociation constant measured by equilibrium binding Scatchard analysis. (4) Ryanodine binding to the low-affinity site can be correlated with a decrease in the dissociation rate constant (k-1) of the high-affinity site, and thereby in the apparent dissociation constant (KD1). The inhibition constant (KI) for inhibiting the high-affinity off rate obtained from a double-reciprocal plot of the change in off rate vs [ryanodine] is practically the same in heart (0.66 microM) and skeletal muscle (0.64 microM) and in the range of the KD2. The binding of cold ryanodine to the low-affinity site appears to lock the bound [3H]ryanodine onto the high-affinity site rather than to exchange with it. Thus, in this sense, the ryanodine receptor exhibits "positive cooperativity".(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the calcium release channel of cardiac and skeletal muscle sarcoplasmic reticulum by target inactivation analysis

The calcium release channel of sarcoplasmic reticulum which triggers muscle contraction in excitation-contraction coupling has recently been isolated. The channel has been found to be morphologically identical with the feet structures of the junctional face membrane of terminal cisternae and consists of an oligomer of a unique high molecular weight polypeptide. In this study, we compare the target size of the calcium release channel from heart and skeletal muscle using target inactivation analysis. The target molecular weights of the calcium release channel estimated by measuring ryanodine binding after irradiation are similar for heart (139,000) and skeletal muscle (143,000) and are smaller than the monomeric unit (estimated to be about 360,000). The target size, estimated by measuring polypeptide remaining after irradiation, was essentially the same for heart and skeletal muscle, 1,061,000 and 1,070,000, respectively, indicating an oligomeric association of protomers. Thus, the calcium release channel of both cardiac and skeletal muscle reacts uniquely with regard to target inactivation analysis in that (1) the size by ryanodine binding is smaller than the monomeric unit and (2) a single hit leads to destruction of more than one polypeptide, by measuring polypeptide remaining. Our target inactivation analysis studies indicate that heart and skeletal muscle receptors are structurally very similar.

Target size of the ryanodine receptor from junctional terminal cisternae of sarcoplasmic reticulum

Target inactivation analysis was carried out on the ryanodine receptor. This receptor recently has been implicated as the channel involved in the calcium release process in excitation-contraction coupling and was localized to the junctional terminal cisternae of sarcoplasmic reticulum from skeletal muscle [Fleischer, S., Ogunbunmi, E. M., Dixon, M. C., & Fleer, E.A.M. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 7256-7259]. Irradiation of the junctional terminal cisternae resulted in an exponential decrease in ryanodine binding with radiation dose, thereby consistent with target theory. The target molecular weight was found to be 138,000 +/- 21,000, i.e., smaller than the polypeptide that binds ryanodine. The calcium pump protein in the same membrane preparation served as an internal control to validate the methodology.