1. Birch RC, Cornish KM, Hocking DR, Trollor JN. {{Understanding the Neuropsychiatric Phenotype of Fragile X-Associated Tremor Ataxia Syndrome: a Systematic Review}}. {Neuropsychol Rev};2014 (May 15)
Fragile X-associated tremor ataxia syndrome (FXTAS) is a recently identified X-linked neurodegenerative disorder affecting a proportion of premutation carriers of the Fragile X Mental Retardation 1 (FMR1) gene. Previous research suggests that cognitive and psychiatric features of FXTAS may include primary impairments in executive function and increased vulnerability to mood and anxiety disorders. A number of these reports, however, are based on overlapping cohorts or have produced inconsistent findings. A systematic review was therefore conducted to further elucidate the neuropsychiatric features characteristic of FXTAS. Fourteen papers met inclusion criteria for the review and were considered to represent nine independent FXTAS cohorts. Findings from the review suggest that the neuropsychiatric phenotype of FXTAS is characterised primarily by poorer performance on measures of executive function, working memory, information processing speed, and fine motor control when compared to matched comparison groups. Two studies were identified in which psychiatric symptoms in FXTAS were compared with controls, and these yielded mixed results. Overall the results of this review support previous reports that the neuropsychiatric profile of FXTAS is consistent with a dysexecutive fronto-subcortical syndrome. However, additional controlled studies are required to progress our understanding of FXTAS and how the neuropsychiatric profile relates to underlying pathological mechanisms.
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2. Cooper M, Thapar A, Jones DK. {{White Matter Microstructure Predicts Autistic Traits in Attention-Deficit/Hyperactivity Disorder}}. {J Autism Dev Disord};2014 (May 15)
Traits of autism spectrum disorder (ASD) in children with attention-deficit/hyperactivity disorder (ADHD) have previously been found to index clinical severity. This study examined the association of ASD traits with diffusion parameters in adolescent males with ADHD (n = 17), and also compared WM microstructure relative to controls (n = 17). Significant associations (p < 0.05, corrected) were found between fractional anisotropy/radial diffusivity and ASD trait severity (positive and negative correlations respectively), mostly in the right posterior limb of the internal capsule/corticospinal tract, right cerebellar peduncle and the midbrain. No case-control differences were found for the diffusion parameters investigated. This is the first report of a WM microstructural signature of autistic traits in ADHD. Thus, even in the absence of full disorder, ASD traits may index a distinctive underlying neurobiology in ADHD.
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3. Cozzolino R, De Magistris L, Saggese P, Stocchero M, Martignetti A, Di Stasio M, Malorni A, Marotta R, Boscaino F, Malorni L. {{Use of solid-phase microextraction coupled to gas chromatography-mass spectrometry for determination of urinary volatile organic compounds in autistic children compared with healthy controls}}. {Anal Bioanal Chem};2014 (May 15)
Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders which have a severe life-long effect on behavior and social functioning, and which are associated with metabolic abnormalities. Their diagnosis is on the basis of behavioral and developmental signs usually detected before three years of age, and there is no reliable biological marker. The objective of this study was to establish the volatile urinary metabolomic profiles of 24 autistic children and 21 healthy children (control group) to investigate volatile organic compounds (VOCs) as potential biomarkers for ASDs. Solid-phase microextraction (SPME) using DVB/CAR/PDMS sorbent coupled with gas chromatography-mass spectrometry was used to obtain the metabolomic information patterns. Urine samples were analyzed under both acid and alkaline pH, to profile a range of urinary components with different physicochemical properties. Multivariate statistics techniques were applied to bioanalytical data to visualize clusters of cases and to detect the VOCs able to differentiate autistic patients from healthy children. In particular, orthogonal projections to latent structures discriminant analysis (OPLS-DA) achieved very good separation between autistic and control groups under both acidic and alkaline pH, identifying discriminating metabolites. Among these, 3-methyl-cyclopentanone, 3-methyl-butanal, 2-methyl-butanal, and hexane under acid conditions, and 2-methyl-pyrazine, 2,3-dimethyl-pyrazine, and isoxazolo under alkaline pH had statistically higher levels in urine samples from autistic children than from the control group. Further investigation with a higher number of patients should be performed to outline the metabolic origins of these variables, define a possible association with ASDs, and verify the usefulness of these variables for early-stage diagnosis.
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4. Lionel AC, Tammimies K, Vaags AK, Rosenfeld JA, Ahn JW, Merico D, Noor A, Runke CK, Pillalamarri VK, Carter MT, Gazzellone MJ, Thiruvahindrapuram B, Fagerberg C, Laulund LW, Pellecchia G, Lamoureux S, Deshpande C, Clayton-Smith J, White AC, Leather S, Trounce J, Melanie Bedford H, Hatchwell E, Eis PS, Yuen RK, Walker S, Uddin M, Geraghty MT, Nikkel SM, Tomiak EM, Fernandez BA, Soreni N, Crosbie J, Arnold PD, Schachar RJ, Roberts W, Paterson AD, So J, Szatmari P, Chrysler C, Woodbury-Smith M, Brian Lowry R, Zwaigenbaum L, Mandyam D, Wei J, Macdonald JR, Howe JL, Nalpathamkalam T, Wang Z, Tolson D, Cobb DS, Wilks TM, Sorensen MJ, Bader PI, An Y, Wu BL, Musumeci SA, Romano C, Postorivo D, Nardone AM, Monica MD, Scarano G, Zoccante L, Novara F, Zuffardi O, Ciccone R, Antona V, Carella M, Zelante L, Cavalli P, Poggiani C, Cavallari U, Argiropoulos B, Chernos J, Brasch-Andersen C, Speevak M, Fichera M, Ogilvie CM, Shen Y, Hodge JC, Talkowski ME, Stavropoulos DJ, Marshall CR, Scherer SW. {{Disruption of the ASTN2/TRIM32 locus at 9q33.1 is a risk factor in males for autism spectrum disorders, ADHD and other neurodevelopmental phenotypes}}. {Hum Mol Genet};2014 (May 15);23(10):2752-2768.
Rare copy number variants (CNVs) disrupting ASTN2 or both ASTN2 and TRIM32 have been reported at 9q33.1 by genome-wide studies in a few individuals with neurodevelopmental disorders (NDDs). The vertebrate-specific astrotactins, ASTN2 and its paralog ASTN1, have key roles in glial-guided neuronal migration during brain development. To determine the prevalence of astrotactin mutations and delineate their associated phenotypic spectrum, we screened ASTN2/TRIM32 and ASTN1 (1q25.2) for exonic CNVs in clinical microarray data from 89 985 individuals across 10 sites, including 64 114 NDD subjects. In this clinical dataset, we identified 46 deletions and 12 duplications affecting ASTN2. Deletions of ASTN1 were much rarer. Deletions near the 3′ terminus of ASTN2, which would disrupt all transcript isoforms (a subset of these deletions also included TRIM32), were significantly enriched in the NDD subjects (P = 0.002) compared with 44 085 population-based controls. Frequent phenotypes observed in individuals with such deletions include autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), speech delay, anxiety and obsessive compulsive disorder (OCD). The 3′-terminal ASTN2 deletions were significantly enriched compared with controls in males with NDDs, but not in females. Upon quantifying ASTN2 human brain RNA, we observed shorter isoforms expressed from an alternative transcription start site of recent evolutionary origin near the 3′ end. Spatiotemporal expression profiling in the human brain revealed consistently high ASTN1 expression while ASTN2 expression peaked in the early embryonic neocortex and postnatal cerebellar cortex. Our findings shed new light on the role of the astrotactins in psychopathology and their interplay in human neurodevelopment.
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5. Liu Z, Smith CB. {{Lithium: A Promising Treatment for Fragile X Syndrome}}. {ACS Chem Neurosci};2014 (May 15)
Fragile X syndrome (FXS) is an inherited disorder that results in intellectual disability and a characteristic behavioral profile that includes autism spectrum disorder, attention deficit hyperactivity disorder, sensory hypersensitivity, hyperarousal, and anxiety. The epigenetic silencing of FMR1 and the consequent absence of its protein product, FMRP, is the most common cause of fragile X. The development of animal models of fragile X syndrome 20 years ago has produced a considerable increase in our understanding of the consequences of the absence of FMRP on the structure and function of the nervous system. Some of the insights gained have led to proposals of treatment strategies that are based on cellular and molecular changes observed in animals lacking FMRP. One such proposal is treatment with lithium, a drug with a long history of clinical efficacy in psychiatry and a drug with newly described uses in degenerative disorders of the nervous system. Lithium treatment has been studied extensively in both mouse and fruit fly models of FXS, and it has been shown to reverse numerous behavioral, physiological, cellular, and molecular phenotypes. A report of a pilot clinical trial on a limited number of adult FXS patients indicated that measurable improvements in behavior and function were seen after 2 months of lithium treatment. A double-blind clinical trial of lithium treatment in FXS patients is now needed.
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6. Yangngam S, Plong-On O, Sripo T, Roongpraiwan R, Hansakunachai T, Wirojanan J, Sombuntham T, Ruangdaraganon N, Limprasert P. {{Mutation Screening of the Neurexin 1 Gene in Thai Patients with Intellectual Disability and Autism Spectrum Disorder}}. {Genet Test Mol Biomarkers};2014 (May 15)
Aim: Neurexin 1 has two major protein isoforms using alternative promoters, coding for the alpha-neurexin 1 (alpha-NRXN1) and beta-neurexin 1 (beta-NRXN1) genes. This study is to explore the possibility that variants of the NRXN1 gene predispose to intellectual disability (ID) and autism spectrum disorder (ASD). Methods: The coding regions in 24 exons and exon-intron boundaries of the NRXN1 gene were investigated in 115 Thai patients with ID and ASD by direct DNA sequencing. Results: Nine novel variants of the NRXN1 gene were identified. Four novel variants were found in the beta-NRXN1 gene, one variant of six GGC repeats in exon 1, and three variants at the 5’UTR. Five novel variants were identified in the alpha-NRXN1 gene, four intronic variants and one missense variant in exon 14 (c.2713T>A or p.F905I). Conclusion: Mutation screening of the NRXN1gene in patients with ID and ASD may be useful to identify potential variants predisposing to ID and ASD. However, further studies utilizing protein functional analysis of the novel variants are required for a more definite conclusion.
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7. Youngster I, Zachor DA, Gabis LV, Bar-Chaim A, Benveniste-Levkovitz P, Britzi M, Soback S, Ziv-Baran T, Berkovitch M. {{CYP2D6 genotyping in paediatric patients with autism treated with risperidone: a preliminary cohort study}}. {Dev Med Child Neurol};2014 (May 15)
AIM: To evaluate the association between cytochrome P450 2D6 (CYP2D6) phenotypes in paediatric patients with autistic spectrum disorders (ASD) treated with risperidone, adverse drug reactions (ADRs), and drug efficacy. METHOD: An observational cohort study of 40 children (34 males, six females; median age 7y range 3-18y) with autistic disorder, pervasive developmental disorder not otherwise specified, or Asperger syndrome diagnosed using the Autism Diagnostic Interview-Revised and treated with risperidone for at least 3 months. Charts were reviewed for demographic and clinical information, response to treatment was assessed by parents and the treating neurologist on a three-point scale, and information about ADRs was collected. Trough plasma levels of risperidone and its metabolites were determined and CYP2D6 genotyping was performed. RESULTS: Twenty-six patients responded to therapy and 11 patients exhibited ADRs. CYP2D6 genotyping showed two patients to be poor metabolizers, two ultra-rapid metabolizers, seven intermediate metabolizers, and 29 extensive metabolizers. Both ultra-rapid metabolizer patients were non-responders and had no ADRs. In contrast, both poor metabolizer patients were responders but experienced ADRs. No correlation was found between risperidone dosage and either risperidone or drug metabolite plasma levels. There was no difference in risperidone or metabolite plasma levels when comparing responders to non-responders, or when comparing patients with or without ADRs. INTERPRETATION: In patients with ASD treated with risperidone, a CYP2D6 phenotype may be associated with response to treatment and development of ADRs.
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8. Zhang W, Cheng Y, Li Y, Chen Z, Jin P, Chen D. {{A feed-forward mechanism involving Drosophila fragile X mental retardation protein triggers a replication stress-induced DNA damage response}}. {Hum Mol Genet};2014 (May 15)
Fragile X syndrome, a common form of inherited mental retardation, is caused by loss of the fragile X mental retardation protein (FMRP). As a selective RNA-binding protein, FMRP is localized predominately in cytoplasm, where it regulates translational control. However, there is a small portion of FMRP present in the nucleus, and its function there has been elusive. Here we show that Drosophila dFMR1 in nucleus is required for replication stress-induced H2Av phosphorylation in the DNA damage response (DDR). Replication stress could induce the expression of dFmr1 and promote the nuclear accumulation of dFMR1. We show that, upon the stimulation of replication stress, dFMR1 is associated with chromatin in a domain-specific manner, which is essential for its ability to induce the phosphorylation of H2Av. These results together reveal an unexpected nuclear role of FMRP in DDR and uncover a feed-forward mechanism by which dFmr1 and early DDR induced by replication stress reciprocally regulate each other, thereby synergistically triggering activity of the DDR signaling cascade.
