STX209 (Arbaclofen) for Autism Spectrum Disorders: An 8-Week Open-Label Study

STX209 (arbaclofen), a selective GABA-B agonist, is hypothesized to modulate the balance of excitatory to inhibitory neurotransmission, and has shown preliminary evidence of benefit in fragile X syndrome. We evaluated its safety, tolerability, and efficacy in non-syndromic autism spectrum disorders, in an 8-week open-label trial enrolling 32 children and adolescents with either Autistic Disorder or Pervasive Developmental Disorder—Not Otherwise Specified, and a score ≥17 on the Aberrant Behavior Checklist (ABC)—Irritability subscale. STX209 was generally well-tolerated. The most common adverse events were agitation and irritability, which typically resolved without dose changes, and were often felt to represent spontaneous variation in underlying symptoms. Improvements were observed on several outcome measures in this exploratory trial, including the ABC-Irritability (the primary endpoint) and the Lethargy/Social Withdrawal subscales, the Social Responsiveness Scale, the CY-BOCS-PDD, and clinical global impression scales. Placebo-controlled study of STX209 is warranted.Seaside Therapeutics Inc

Genetic background modulates phenotypes of serotonin transporter Ala56 knock-in mice

BACKGROUND: Previously, we identified multiple, rare serotonin (5-HT) transporter (SERT) variants in children with autism spectrum disorder (ASD). Although in our study the SERT Ala56 variant was over-transmitted to ASD probands, it was also seen in some unaffected individuals, suggesting that associated ASD risk is influenced by the epistatic effects of other genetic variation. Subsequently, we established that mice expressing the SERT Ala56 variant on a 129S6/S4 genetic background display multiple biochemical, physiological and behavioral changes, including hyperserotonemia, altered 5-HT receptor sensitivity, and altered social, communication, and repetitive behavior. Here we explore the effects of genetic background on SERT Ala56 knock-in phenotypes. METHODS: To explore the effects of genetic background, we backcrossed SERT Ala56 mice on the 129 background into a C57BL/6 (B6) background to achieve congenic B6 SERT Ala56 mice, and assessed autism-relevant behavior, including sociability, ultrasonic vocalizations, and repetitive behavior in the home cage, as well as serotonergic phenotypes, including whole blood serotonin levels and serotonin receptor sensitivity. RESULTS: One consistent phenotype between the two strains was performance in the tube test for dominance, where mutant mice displayed a greater tendency to withdraw from a social encounter in a narrow tube as compared to wildtype littermate controls. On the B6 background, mutant pup ultrasonic vocalizations were significantly increased, in contrast to decreased vocalizations seen previously on the 129 background. Several phenotypes seen on the 129 background were reduced or absent when the mutation was placed on the B6 background, including hyperserotonemia, 5-HT receptor hypersensivity, and repetitive behavior. CONCLUSIONS: Our findings provide a cogent example of how epistatic interactions can modulate the impact of functional genetic variation and suggest that some aspects of social behavior may be especially sensitive to changes in SERT function. Finally, these results provide a platform for the identification of genes that may modulate the risk of ASD in humans

Associations between cytokines, endocrine stress response, and gastrointestinal symptoms in autism spectrum disorder

PosterAutism spectrum disorder (ASD) is characterized by impairments in social communication and abnormal repetitive behavior patterns. Recent studies have shown a strong association between ASD and gastrointestinal (GI) symptomatology. Some individuals with ASD show altered reactivity to stress, as well as altered immune markers, particularly stress responsive cytokines including TNF-alpha and IL-6. To assess potential relationships between GI symptoms and stress response, we examined whether GI symptoms are associated with increases in stress-associated endocrine markers and cytokines in ASD. We also conducted exploratory analyses the examine the relationship between IL-6, TNF-alpha, cortisol, and intelligence, as well as the effects of the presence or absence of co-occurring medical conditions on the relationship between IL-6, TNF-alpha, cortisol, and GI symptoms. Given the aforementioned findings, we expected to find positive relationships between GI symptoms and biomarkers of stress, including cortisol levels, IL-6, and TNF-alpha

Mutation analysis of the NSD1 gene in patients with autism spectrum disorders and macrocephaly

<p>Abstract</p> <p>Background</p> <p>Sotos syndrome is an overgrowth syndrome characterized by macrocephaly, advanced bone age, characteristic facial features, and learning disabilities, caused by mutations or deletions of the <it>NSD1 </it>gene, located at 5q35. Sotos syndrome has been described in a number of patients with autism spectrum disorders, suggesting that <it>NSD1 </it>could be involved in other cases of autism and macrocephaly.</p> <p>Methods</p> <p>We screened the <it>NSD1 </it>gene for mutations and deletions in 88 patients with autism spectrum disorders and macrocephaly (head circumference 2 standard deviations or more above the mean). Mutation analysis was performed by direct sequencing of all exons and flanking regions. Dosage analysis of <it>NSD1 </it>was carried out using multiplex ligation-dependent probe amplification.</p> <p>Results</p> <p>We identified three missense variants (R604L, S822C and E1499G) in one patient each, but none is within a functional domain. In addition, segregation analysis showed that all variants were inherited from healthy parents and in two cases were also present in unaffected siblings, indicating that they are probably nonpathogenic. No partial or whole gene deletions/duplications were observed.</p> <p>Conclusion</p> <p>Our findings suggest that Sotos syndrome is a rare cause of autism spectrum disorders and that screening for <it>NSD1 </it>mutations and deletions in patients with autism and macrocephaly is not warranted in the absence of other features of Sotos syndrome.</p

Dysregulation of the Norepinephrine Transporter Sustains Cortical Hypodopaminergia and Schizophrenia-Like Behaviors in Neuronal Rictor Null Mice

A novel animal model highlights the link between Akt dysfunction, reduced cortical dopamine function, norepinephrine transporters, and schizophrenia-like behaviors

Modeling rare gene variation to gain insight into the oldest biomarker in autism: construction of the serotonin transporter Gly56Ala knock-in mouse

Alterations in peripheral and central indices of serotonin (5-hydroxytryptamine, 5-HT) production, storage and signaling have long been associated with autism. The 5-HT transporter gene (HTT, SERT, SLC6A4) has received considerable attention as a potential risk locus for autism-spectrum disorders, as well as disorders with overlapping symptoms, including obsessive-compulsive disorder (OCD). Here, we review our efforts to characterize rare, nonsynonymous polymorphisms in SERT derived from multiplex pedigrees carrying diagnoses of autism and OCD and present the initial stages of our effort to model one of these variants, Gly56Ala, in vivo. We generated a targeting vector to produce the Gly56Ala substitution in the Slc6a4 locus by homologous recombination. Following removal of a neomycin resistance selection cassette, animals exhibiting germline transmission of the Ala56 variant were bred to establish a breeding colony on a 129S6 background, suitable for initial evaluation of biochemical, physiological and behavioral alterations relative to SERT Gly56 (wildtype) animals. SERT Ala56 mice were achieved and exhibit a normal pattern of transmission. The initial growth and gross morphology of these animals is comparable to wildtype littermate controls. The SERT Ala56 variant can be propagated in 129S6 mice without apparent disruption of fertility and growth. We discuss both the opportunities and challenges that await the physiological/behavioral analysis of Gly56Ala transgenic mice, with particular reference to modeling autism-associated traits

Partitioning the Heritability of Tourette Syndrome and Obsessive Compulsive Disorder Reveals Differences in Genetic Architecture

The direct estimation of heritability from genome-wide common variant data as implemented in the program Genome-wide Complex Trait Analysis (GCTA) has provided a means to quantify heritability attributable to all interrogated variants. We have quantified the variance in liability to disease explained