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Disruption of DNA-methylation-dependent long gene repression in Rett syndrome.

June 26, 2015 - 6:11am
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Disruption of DNA-methylation-dependent long gene repression in Rett syndrome.

Nature. 2015 Jun 4;522(7554):89-93

Authors: Gabel HW, Kinde B, Stroud H, Gilbert CS, Harmin DA, Kastan NR, Hemberg M, Ebert DH, Greenberg ME

Abstract
Disruption of the MECP2 gene leads to Rett syndrome (RTT), a severe neurological disorder with features of autism. MECP2 encodes a methyl-DNA-binding protein that has been proposed to function as a transcriptional repressor, but despite numerous mouse studies examining neuronal gene expression in Mecp2 mutants, no clear model has emerged for how MeCP2 protein regulates transcription. Here we identify a genome-wide length-dependent increase in gene expression in MeCP2 mutant mouse models and human RTT brains. We present evidence that MeCP2 represses gene expression by binding to methylated CA sites within long genes, and that in neurons lacking MeCP2, decreasing the expression of long genes attenuates RTT-associated cellular deficits. In addition, we find that long genes as a population are enriched for neuronal functions and selectively expressed in the brain. These findings suggest that mutations in MeCP2 may cause neurological dysfunction by specifically disrupting long gene expression in the brain.

PMID: 25762136 [PubMed - indexed for MEDLINE]

MACROD2 gene associated with autistic-like traits in a general population sample.

June 26, 2015 - 6:11am
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MACROD2 gene associated with autistic-like traits in a general population sample.

Psychiatr Genet. 2014 Dec;24(6):241-8

Authors: Jones RM, Cadby G, Blangero J, Abraham LJ, Whitehouse AJ, Moses EK

Abstract
There is now substantial evidence that autistic-like traits in the general population lie on a continuum, with clinical autism spectrum disorders (ASD) representing the extreme end of this distribution. In this study, we sought to evaluate five independently identified genetic associations with ASD with autistic-like traits in the general population. In the study cohort, clinical phenotype and genomewide association genotype data were obtained from the Western Australian Pregnancy Cohort (Raine) Study. The outcome measure used was the Autism Spectrum Quotient (AQ), a quantitative measure of autistic-like traits of individuals in the cohort. Total AQ scores were calculated for each individual, as well as scores for three subscales. Five candidate single nucleotide polymorphism (SNP) associations with ASD, reported in previously published genomewide association studies, were selected using a nominal cutoff value of P less than 1.0×10. We tested whether these five SNPs were associated with total AQ and the subscales, after adjustment for possible confounders. SNP rs4141463 located in the macro domain containing 2 (MACROD2) gene was significantly associated with the Communication/Mindreading subscale. No other SNP was significantly associated with total AQ or the subscales. The MACROD2 gene is a strong positional candidate risk factor for autistic-like traits in the general population.

PMID: 25360606 [PubMed - indexed for MEDLINE]

Association study identifying a new susceptibility gene (AUTS2) for schizophrenia.

June 26, 2015 - 6:11am
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Association study identifying a new susceptibility gene (AUTS2) for schizophrenia.

Int J Mol Sci. 2014;15(11):19406-16

Authors: Zhang B, Xu YH, Wei SG, Zhang HB, Fu DK, Feng ZF, Guan FL, Zhu YS, Li SB

Abstract
Schizophrenia (SCZ) is a severe and debilitating mental disorder, and the specific genetic factors that underlie the risk for SCZ remain elusive. The autism susceptibility candidate 2 (AUTS2) gene has been reported to be associated with autism, suicide, alcohol consumption, and heroin dependence. We hypothesized that AUTS2 might be associated with SCZ. In the present study, three polymorphisms (rs6943555, rs7459368, and rs9886351) in the AUTS2 gene were genotyped in 410 patients with SCZ and 435 controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and forced PCR-RFLP methods. We detected an association between SCZ and the rs6943555 genotype distribution (odds ratio (OR)=1.363, 95% confidence interval (CI): 0.848-2.191, p=0.001). The association remained significant after adjusting for gender, and a significant effect (p=0.001) was observed among the females. In the present study, rs6943555 was determined to be associated with female SCZ. Our results confirm previous reports which have suggested that rs6943555 might elucidate the pathogenesis of schizophrenia and play an important role in its etiology.

PMID: 25347278 [PubMed - indexed for MEDLINE]

Association between autism spectrum disorder in individuals with velocardiofacial (22q11.2 deletion) syndrome and PRODH and COMT genotypes.

June 26, 2015 - 6:11am
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Association between autism spectrum disorder in individuals with velocardiofacial (22q11.2 deletion) syndrome and PRODH and COMT genotypes.

Psychiatr Genet. 2014 Dec;24(6):269-72

Authors: Radoeva PD, Coman IL, Salazar CA, Gentile KL, Higgins AM, Middleton FA, Antshel KM, Fremont W, Shprintzen RJ, Morrow BE, Kates WR

Abstract
Velocardiofacial (VCFS; 22q11.2 deletion) syndrome is a genetic disorder that results from a hemizygous deletion of the q11.2 region on chromosome 22, and is associated with greatly increased risk for psychiatric disorders, including autism spectrum disorder (ASD) and schizophrenia. There is emerging evidence for the involvement of catechol-O-methyltransferase (COMT) and proline dehydrogenase (oxidase) 1 (PRODH) in the psychiatric phenotype of individuals with VCFS. Here, we tested the hypothesis that PRODH and COMT are associated with ASD in youths with VCFS. We found that individuals with VCFS and the low-activity alleles of both PRODH and COMT (rs4819756A and rs4680A) were more likely to present with ASD as compared with individuals with VCFS and the high-activity alleles of these genes [P<0.05; odds ratio=6.0 (95% confidence interval=1.27-28.26; N=87)]. Our results suggest that PRODH and COMT may interact to contribute to the ASD phenotype in individuals with VCFS.

PMID: 25325218 [PubMed - indexed for MEDLINE]

Common and rare variants of the THBS1 gene associated with the risk for autism.

June 26, 2015 - 6:11am
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Common and rare variants of the THBS1 gene associated with the risk for autism.

Psychiatr Genet. 2014 Dec;24(6):235-40

Authors: Lu L, Guo H, Peng Y, Xun G, Liu Y, Xiong Z, Tian D, Liu Y, Li W, Xu X, Zhao J, Hu Z, Xia K

Abstract
OBJECTIVES: Autism is a severe neurodevelopmental disorder. Many susceptible or causative genes have been identified, and most of them are related to synaptogenesis. The THBS1 gene encodes thrombospondin 1, which plays a critical role in synaptogenesis of the central nervous system in the developing brain. However, no study has been carried out revealing that THBS1 is an autism risk gene.
METHODS: We analyzed the whole coding region and the 5'-untranslated region of the THBS1 gene in 313 autistic patients by Sanger sequencing, which was also used to analyze the identified variants in 350 normal controls. Association analysis was carried out using PLINK or R. Haplotype analysis was carried out using Haploview. Functional prediction and conservation analysis of missense variants were carried out using ANNOVAR.
RESULTS: Twelve variants, including five common variants and seven rare variants, were identified in the THBS1 coding region and the 5'-untranslated region. Among them, one common variant (c.1567A>G:p.T523A) was significantly associated with autism (P<0.05). Two rare variants (c.2429G>A:p.R810Q, c.3496G>C:p.E1166Q) were absent in the 350 controls and were not reported in the single nucleotide polymorphism database (dbSNP). Combined association analysis of the rare variants (minor allele frequency<0.01) in patients and Asian samples in the 1000 genome project revealed a significant association between these rare variants and autism (P=0.039).
CONCLUSION: Our data revealed that both common and rare variants of the THBS1 gene are associated with risk for autism, suggesting that THBS1 is a novel susceptible gene for autism.

PMID: 25304225 [PubMed - indexed for MEDLINE]

The clinical impact of chromosomal microarray on paediatric care in Hong Kong.

June 25, 2015 - 9:56am
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The clinical impact of chromosomal microarray on paediatric care in Hong Kong.

PLoS One. 2014;9(10):e109629

Authors: Tao VQ, Chan KY, Chu YW, Mok GT, Tan TY, Yang W, Lee SL, Tang WF, Tso WW, Lau ET, Kan AS, Tang MH, Lau YL, Chung BH

Abstract
OBJECTIVE: To evaluate the clinical impact of chromosomal microarray (CMA) on the management of paediatric patients in Hong Kong.
METHODS: We performed NimbleGen 135k oligonucleotide array on 327 children with intellectual disability (ID)/developmental delay (DD), autism spectrum disorders (ASD), and/or multiple congenital anomalies (MCAs) in a university-affiliated paediatric unit from January 2011 to May 2013. The medical records of patients were reviewed in September 2013, focusing on the pathogenic/likely pathogenic CMA findings and their "clinical actionability" based on established criteria.
RESULTS: Thirty-seven patients were reported to have pathogenic/likely pathogenic results, while 40 had findings of unknown significance. This gives a detection rate of 11% for clinically significant (pathogenic/likely pathogenic) findings. The significant findings have prompted clinical actions in 28 out of 37 patients (75.7%), while the findings with unknown significance have led to further management recommendation in only 1 patient (p < 0.001). Nineteen out of the 28 management recommendations are "evidence-based" on either practice guidelines endorsed by a professional society (n = 9, Level 1) or peer-reviewed publications making medical management recommendation (n = 10, Level 2). CMA results impact medical management by precipitating referral to a specialist (n = 24); diagnostic testing (n = 25), surveillance of complications (n = 19), interventional procedure (n = 7), medication (n = 15) or lifestyle modification (n = 12).
CONCLUSION: The application of CMA in children with ID/DD, ASD, and/or MCAs in Hong Kong results in a diagnostic yield of ∼ 11% for pathogenic/likely pathogenic results. Importantly the yield for clinically actionable results is 8.6%. We advocate using diagnostic yield of clinically actionable results to evaluate CMA as it provides information of both clinical validity and clinical utility. Furthermore, it incorporates evidence-based medicine into the practice of genomic medicine. The same framework can be applied to other genomic testing strategies enabled by next-generation sequencing.

PMID: 25333781 [PubMed - indexed for MEDLINE]

The dwarf phenotype in GH240B mice, haploinsufficient for the autism candidate gene Neurobeachin, is caused by ectopic expression of recombinant human growth hormone.

June 25, 2015 - 9:56am
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The dwarf phenotype in GH240B mice, haploinsufficient for the autism candidate gene Neurobeachin, is caused by ectopic expression of recombinant human growth hormone.

PLoS One. 2014;9(10):e109598

Authors: Nuytens K, Tuand K, Fu Q, Stijnen P, Pruniau V, Meulemans S, Vankelecom H, Creemers JW

Abstract
Two knockout mouse models for the autism candidate gene Neurobeachin (Nbea) have been generated independently. Although both models have similar phenotypes, one striking difference is the dwarf phenotype observed in the heterozygous configuration of the GH240B model that is generated by the serendipitous insertion of a promoterless human growth hormone (hGH) genomic fragment in the Nbea gene. In order to elucidate this discrepancy, the dwarfism present in this Nbea mouse model was investigated in detail. The growth deficiency in Nbea+/- mice coincided with an increased percentage of fat mass and a decrease in bone mineral density. Low but detectable levels of hGH were detected in the pituitary and hypothalamus of Nbea+/- mice but not in liver, hippocampus nor in serum. As a consequence, several members of the mouse growth hormone (mGH) signaling cascade showed altered mRNA levels, including a reduction in growth hormone-releasing hormone mRNA in the hypothalamus. Moreover, somatotrope cells were less numerous in the pituitary of Nbea+/- mice and both contained and secreted significantly less mGH resulting in reduced levels of circulating insulin-like growth factor 1. These findings demonstrate that the random integration of the hGH transgene in this mouse model has not only inactivated Nbea but has also resulted in the tissue-specific expression of hGH causing a negative feedback loop, mGH hyposecretion and dwarfism.

PMID: 25333629 [PubMed - indexed for MEDLINE]

Female Autism Phenotypes Investigated at Different Levels of Language and Developmental Abilities.

June 24, 2015 - 8:59am
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Female Autism Phenotypes Investigated at Different Levels of Language and Developmental Abilities.

J Autism Dev Disord. 2015 Jun 23;

Authors: Howe YJ, O'Rourke JA, Yatchmink Y, Viscidi EW, Jones RN, Morrow EM

Abstract
This study investigated the differences in clinical symptoms between females and males with autism spectrum disorder (ASD) across three verbal ability groups (nonverbal, phrase and fluent speech), based on which Autism Diagnostic Observation Schedule module was administered to 5723 individuals in four research datasets. In the Simons Simplex Collection and Autism Treatment Network, females with ASD and phrase or fluent speech had lower cognitive, adaptive, and social abilities than males. In the Autism Genetics Resource Exchange and the Autism Consortium, females with phrase or fluent speech had similar or better adaptive and social abilities than males. Females who were nonverbal had similar cognitive, adaptive, and social abilities as males. Population-based longitudinal studies of verbally fluent females with ASD are needed.

PMID: 26100851 [PubMed - as supplied by publisher]

Repeated positive fighting experience in male inbred mice.

June 24, 2015 - 8:59am
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Repeated positive fighting experience in male inbred mice.

Nat Protoc. 2014 Nov;9(11):2705-17

Authors: Kudryavtseva NN, Smagin DA, Kovalenko IL, Vishnivetskaya GB

Abstract
Repeated aggression is a frequent symptom of many psychiatric and neurological disorders, including obsessive-compulsive and attention deficit hyperactivity disorders, bipolar and post-traumatic stress disorders, epilepsy, autism, schizophrenia and drug abuse. However, repeated aggression is insufficiently studied because there is a lack of adequate models in animals. The sensory contact model (SCM), widely used to study the effects of chronic social defeat stress, can also be used to investigate the effects of repeated aggression. Mice with repeated positive fighting experience in daily agonistic interactions in this model develop pronounced aggressiveness, anxiety and impulsivity, disturbances in motivated and cognitive behaviors, and impairments of sociability; they also demonstrate hyperactivity, attention-deficit behavior, motor dysfunctions and repetitive stereotyped behaviors, such as jerks, rotations and head twitches. In this protocol, we describe how to apply the SCM to study repeated aggression in mice. Severe neuropathology develops in male mice after 20-21 d of agonistic interactions.

PMID: 25340443 [PubMed - indexed for MEDLINE]

Investigation of 15q11-q13, 16p11.2 and 22q13 CNVs in autism spectrum disorder Brazilian individuals with and without epilepsy.

June 24, 2015 - 8:59am
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Investigation of 15q11-q13, 16p11.2 and 22q13 CNVs in autism spectrum disorder Brazilian individuals with and without epilepsy.

PLoS One. 2014;9(9):e107705

Authors: Moreira DP, Griesi-Oliveira K, Bossolani-Martins AL, Lourenço NC, Takahashi VN, da Rocha KM, Moreira ES, Vadasz E, Meira JG, Bertola D, O'Halloran E, Magalhães TR, Fett-Conte AC, Passos-Bueno MR

Abstract
Copy number variations (CNVs) are an important cause of ASD and those located at 15q11-q13, 16p11.2 and 22q13 have been reported as the most frequent. These CNVs exhibit variable clinical expressivity and those at 15q11-q13 and 16p11.2 also show incomplete penetrance. In the present work, through multiplex ligation-dependent probe amplification (MLPA) analysis of 531 ethnically admixed ASD-affected Brazilian individuals, we found that the combined prevalence of the 15q11-q13, 16p11.2 and 22q13 CNVs is 2.1% (11/531). Parental origin could be determined in 8 of the affected individuals, and revealed that 4 of the CNVs represent de novo events. Based on CNV prediction analysis from genome-wide SNP arrays, the size of those CNVs ranged from 206 kb to 2.27 Mb and those at 15q11-q13 were limited to the 15q13.3 region. In addition, this analysis also revealed 6 additional CNVs in 5 out of 11 affected individuals. Finally, we observed that the combined prevalence of CNVs at 15q13.3 and 22q13 in ASD-affected individuals with epilepsy (6.4%) was higher than that in ASD-affected individuals without epilepsy (1.3%; p<0.014). Therefore, our data show that the prevalence of CNVs at 15q13.3, 16p11.2 and 22q13 in Brazilian ASD-affected individuals is comparable to that estimated for ASD-affected individuals of pure or predominant European ancestry. Also, it suggests that the likelihood of a greater number of positive MLPA results might be found for the 15q13.3 and 22q13 regions by prioritizing ASD-affected individuals with epilepsy.

PMID: 25255310 [PubMed - indexed for MEDLINE]

The applications of pharmacogenomics to neurological disorders.

June 24, 2015 - 8:59am
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The applications of pharmacogenomics to neurological disorders.

Curr Mol Med. 2014;14(7):880-90

Authors: Gilman C, McSweeney C, Mao Y

Abstract
The most common neurological disorders, including neurodegenerative diseases and psychiatric disorders, have received recent attention with regards to pharmacogenomics and personalized medicine. Here, we will focus on a neglected neurodegenerative disorder, cerebral ischemic stroke (CIS), and highlight recent advances in two disorders, Parkinson's disease (PD) and Alzheimer's diseases (AD), that possess both similar and distinct mechanisms in regards to potential therapeutic targets. In the first part of this review, we will focus primarily on mechanisms that are somewhat specific to each disorder which are involved in neurodegeneration (i.e., protease pathways, calcium homeostasis, reactive oxygen species regulation, DNA repair mechanisms, neurogenesis regulation, mitochondrial function, etc.). In the second part of this review, we will discuss the applications of the genome-wide technology on pharmacogenomics of mental illnesses including schizophrenia (SCZ), autism spectrum disorders (ASD), attention deficit hyperactivity disorder (ADHD), and obsessive compulsive disorder (OCD).

PMID: 25109797 [PubMed - indexed for MEDLINE]

'What's up, (R)DoC?'--can identifying core dimensions of early functioning help us understand, and then reduce, developmental risk for mental disorders?

June 24, 2015 - 8:59am
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'What's up, (R)DoC?'--can identifying core dimensions of early functioning help us understand, and then reduce, developmental risk for mental disorders?

J Child Psychol Psychiatry. 2014 Aug;55(8):849-51

Authors: Sonuga-Barke EJ

Abstract
In the U.S. the National Institute of Mental Health (NIMH), the main funder of mental health research in the world, has recently changed its funding model to promote a radically new perspective for mental health science. This bold, and for some controversial, initiative, termed the Research Diagnostic Criteria (or RDoC for short), intends to shift the focus of research, and eventually clinical practice, away from existing diagnostic categories, as recently updated in the DSM-5, towards 'new ways of classifying psychopathology based on dimensions of observable behavior and neurobiological measures.' This reorientation from discrete categorical disorder manifestations to underlying cross-cutting dimensions of individual functioning has generated considerable debate across the community of mental health researchers and clinicians (with strong views voiced both pro and con). Given its pivotal role in defining the research agenda globally, there is little doubt that this US science funding initiative will also have ramifications for researchers and clinicians worldwide. In this Editorial we focus specifically on the translational potential of the dimensional RDoC approach, properly extended to developmental models of early risk, in terms of its value as a potential driver of early intervention/prevention models; in the current issue of the JCPP this is exemplified by a number of papers thata address the mapping of underlying dimensions of core functioning to disorder risk, providing evidence for their potential predictive power as early markers of later disorder processes.

PMID: 25039570 [PubMed - indexed for MEDLINE]

A familial heterozygous null mutation of MET in autism spectrum disorder.

June 24, 2015 - 8:59am
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A familial heterozygous null mutation of MET in autism spectrum disorder.

Autism Res. 2014 Oct;7(5):617-22

Authors: Lambert N, Wermenbol V, Pichon B, Acosta S, van den Ameele J, Perazzolo C, Messina D, Musumeci MF, Dessars B, De Leener A, Abramowicz M, Vilain C

Abstract
Autism spectrum disorder (ASD) results from interactions of genetic and environmental factors. The MET proto-oncogene has been identified as a candidate gene for autism susceptibility, and is implicated in neurodevelopment and social brain circuitry. Here, we describe the first case of a familial mutation of MET, consisting of an interstitial genomic deletion removing exons 12 through 15, causing a frameshift and premature stop codon, with evidence of nonsense-mediated mRNA decay. On the other allele, patients carried the C allele of the MET promoter rs1858830 polymorphism, known to decrease MET expression and previously associated with autism susceptibility. The heterozygous mutation was associated with autism in one patient, and language and social impairment in a sibling. Our observations delineate the phenotypic spectrum associated with a clearly defined, very likely complete loss of function mutation of MET. Incomplete penetrance in this family was consistent with MET as a partial susceptibility gene for ASD. Implication of MET in normal and pathological brain development opens new perspectives for understanding the pathophysiology of autism and for eventual therapeutical clues.

PMID: 24909855 [PubMed - indexed for MEDLINE]

Brief report: impact of child problem behaviors and parental broad autism phenotype traits on substance use among parents of children with ASD.

June 24, 2015 - 8:59am
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Brief report: impact of child problem behaviors and parental broad autism phenotype traits on substance use among parents of children with ASD.

J Autism Dev Disord. 2014 Oct;44(10):2621-7

Authors: Wade JL, Cox NB, Reeve RE, Hull M

Abstract
Using data from the Simons Simplex Collection, the present study examined the impact of child externalizing behavior and parental broad autism phenotype traits on substance use among parents of children with autism spectrum disorder (n = 2,388). For both fathers and mothers, child externalizing behaviors predicted tobacco use (OR = 1.01 and OR = 1.02, respectively), whereas rigidity increased risk of tobacco use for fathers (OR = 1.29) but not mothers. Additionally, among mothers, child externalizing behaviors increased risk of illegal substance use (OR = 1.04), whereas maternal rigidity decreased risk of alcohol use (OR = .83). Collectively, results suggest that child externalizing behaviors and parental rigidity may have differing impacts on the types of substances used by parents.

PMID: 24805795 [PubMed - indexed for MEDLINE]

Developing with ring 14 syndrome: a survey in different countries.

June 24, 2015 - 8:59am
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Developing with ring 14 syndrome: a survey in different countries.

Clin Linguist Phon. 2014 Nov;28(11):844-56

Authors: Zampini L, Zanchi P, D'Odorico L

Abstract
This study aimed to assess the communicative skills of children and young adults with ring 14 syndrome and linear 14q deletions, investigating the relationships among their language development and their genetic, clinical, psychomotor and behavioural characteristics. Participants were 36 individuals with chromosome 14 aberrations whose parents completed a questionnaire, specifically developed in five languages, to assess their son's/daughter's development. Data analysis showed that chronological age does not account for the high individual variability found in the participants' skills. The comparison between participants with ring 14 syndrome and participants with 14q linear deletions showed that the former were characterised by a higher occurrence of epilepsy, abnormalities of the retina and autism. The participants with smaller amounts of deleted genetic material were those who had a higher level of language development. Because ring 14 syndrome is a rare genetic disease, the collection of data from a large group of individuals could be helpful to create expectations about the possible developmental outcomes of these children.

PMID: 24779649 [PubMed - indexed for MEDLINE]

Brief report: functional MRI of a patient with 7q11.23 duplication syndrome and autism spectrum disorder.

June 24, 2015 - 8:59am
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Brief report: functional MRI of a patient with 7q11.23 duplication syndrome and autism spectrum disorder.

J Autism Dev Disord. 2014 Oct;44(10):2608-13

Authors: Prontera P, Serino D, Caldini B, Scarponi L, Merla G, Testa G, Muti M, Napolioni V, Mazzotta G, Piccirilli M, Donti E

Abstract
The duplication of the Williams-Beuren syndrome (WBS) region (7q11.23) is a copy number variant associated with autism spectrum disorder (ASD). One of the most intriguing aspects is that the reciprocal microdeletion causes WBS, characterized by hypersociability, marked empathy, and a relative capacity in verbal short-term memory and language. Herein, we studied, by using functional morphological and volumetric magnetic resonance, a 17-year-old male patient who displays a de novo 7q11.23 duplication and ASD. The limbic system of the patient appeared hypo-functional, while the total brain volume was increased, thus contrasting, in an opposite and intriguing manner, with the global brain volume reduction reported in WBS. Even if these findings come from the analysis of a single patient and, therefore, have to be considered preliminary results, they encourage carrying on further functional and volumetric studies in patients with 7q11.23 duplication, to fully elucidate the role of this gene-dosage alteration on brain development and limbic system function.

PMID: 24722762 [PubMed - indexed for MEDLINE]

X-linked focal epilepsy with reflex bathing seizures: Characterization of a distinct epileptic syndrome.

June 23, 2015 - 6:42am
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X-linked focal epilepsy with reflex bathing seizures: Characterization of a distinct epileptic syndrome.

Epilepsia. 2015 Jun 19;

Authors: Nguyen DK, Rouleau I, Sénéchal G, Ansaldo AI, Gravel M, Benfenati F, Cossette P

Abstract
OBJECTIVE: We recently reported a Q555X mutation of synapsin 1 (SYN1) on chromosome Xp11-q21 in a family segregating partial epilepsy and autistic spectrum disorder. Herein, we provide a detailed description of the epileptic syndrome in the original family.
METHODS: A total of 34 members from a large French-Canadian family were evaluated. Family members with seizures or epilepsy underwent (when possible) clinical, neuropsychological, electrophysiologic, and neuroimaging assessments.
RESULTS: Epilepsy was diagnosed in 10 family members (4 deceased, 6 living). In addition to occasional spontaneous complex partial seizures, seven family members clearly had reflex seizures triggered by bathing or showering. Hippocampal atrophy was found in two of five epileptic family members family members who underwent magnetic resonance (MR) imaging. Video-electroencephalography (EEG) recordings of three triggered seizures in two affected members showed rhythmic theta activity over temporal head regions. Ictal single-photon emission computed tomography (SPECT) showed temporoinsular perfusion changes. Detailed neuropsychological assessments revealed that SYN1 Q555X male mutation carriers showed specific language impairment and mild autistic spectrum disorder. Female carriers also exhibited reading impairments and febrile seizures but no chronic epilepsy.
SIGNIFICANCE: Available evidence suggests that impaired SYN1 function is associated with hyperexcitability of the temporoinsular network and disturbance of high mental functions such as language and social interaction. The presence of reflex bathing seizures, a most peculiar clinical feature, could be helpful in identifying other patients with this syndrome.

PMID: 26096837 [PubMed - as supplied by publisher]

The Human Clinical Phenotypes of Altered CHRNA7 Copy Number.

June 23, 2015 - 6:42am
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The Human Clinical Phenotypes of Altered CHRNA7 Copy Number.

Biochem Pharmacol. 2015 Jun 18;

Authors: Gillentine M, Schaaf C

Abstract
Copy number variants (CNVs) have been implicated in multiple neuropsychiatric conditions, including autism spectrum disorder (ASD), schizophrenia, and intellectual disability (ID). Chromosome 15q13 is a hotspot for such CNVs due to the presence of low copy repeat (LCR) elements, which facilitate non-allelic homologous recombination (NAHR). Several of these CNVs have been overrepresented in individuals with neuropsychiatric disorders; yet variable expressivity and incomplete penetrance are commonly seen. Dosage sensitivity of the CHRNA7 gene, which encodes for the α7 nicotinic acetylcholine receptor in the human brain, has been proposed to have a major contribution to the observed cognitive and behavioral phenotypes, as it represents the smallest region of overlap to all the 15q13.3 deletions and duplications. Individuals with zero to four copies of CHRNA7 have been reported in the literature, and represent a range of clinical severity, with deletions causing generally more severe and more highly penetrant phenotypes. Potential mechanisms to account for the variable expressivity within each group of 15q13.3 CNVs will be discussed.

PMID: 26095975 [PubMed - as supplied by publisher]

Paired-Duplication Signatures Mark Cryptic Inversions and Other Complex Structural Variation.

June 23, 2015 - 6:42am
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Paired-Duplication Signatures Mark Cryptic Inversions and Other Complex Structural Variation.

Am J Hum Genet. 2015 Jun 17;

Authors: Brand H, Collins RL, Hanscom C, Rosenfeld JA, Pillalamarri V, Stone MR, Kelley F, Mason T, Margolin L, Eggert S, Mitchell E, Hodge JC, Gusella JF, Sanders SJ, Talkowski ME

Abstract
Copy-number variants (CNVs) have been the predominant focus of genetic studies of structural variation, and chromosomal microarray (CMA) for genome-wide CNV detection is the recommended first-tier genetic diagnostic screen in neurodevelopmental disorders. We compared CNVs observed by CMA to the structural variation detected by whole-genome large-insert sequencing in 259 individuals diagnosed with autism spectrum disorder (ASD) from the Simons Simplex Collection. These analyses revealed a diverse landscape of complex duplications in the human genome. One remarkably common class of complex rearrangement, which we term dupINVdup, involves two closely located duplications ("paired duplications") that flank the breakpoints of an inversion. This complex variant class is cryptic to CMA, but we observed it in 8.1% of all subjects. We also detected other paired-duplication signatures and duplication-mediated complex rearrangements in 15.8% of all ASD subjects. Breakpoint analysis showed that the predominant mechanism of formation of these complex duplication-associated variants was microhomology-mediated repair. On the basis of the striking prevalence of dupINVdups in this cohort, we explored the landscape of all inversion variation among the 235 highest-quality libraries and found abundant complexity among these variants: only 39.3% of inversions were canonical, or simple, inversions without additional rearrangement. Collectively, these findings indicate that dupINVdups, as well as other complex duplication-associated rearrangements, represent relatively common sources of genomic variation that is cryptic to population-based microarray and low-depth whole-genome sequencing. They also suggest that paired-duplication signatures detected by CMA warrant further scrutiny in genetic diagnostic testing given that they might mark complex rearrangements of potential clinical relevance.

PMID: 26094575 [PubMed - as supplied by publisher]

A critical role of RBM8a in proliferation and differentiation of embryonic neural progenitors.

June 22, 2015 - 6:52am

A critical role of RBM8a in proliferation and differentiation of embryonic neural progenitors.

Neural Dev. 2015 Jun 21;10(1):18

Authors: Zou D, McSweeney C, Sebastian A, Reynolds DJ, Dong F, Zhou Y, Deng D, Wang Y, Liu L, Zhu J, Zou J, Shi Y, Albert I, Mao Y

Abstract
BACKGROUND: Nonsense mediated mRNA decay (NMD) is an RNA surveillance mechanism that controls RNA stability and ensures the speedy degradation of erroneous and unnecessary transcripts. This mechanism depends on several core factors in the exon junction complex (EJC), eIF4A3, RBM8a, Magoh, and BTZ, as well as peripheral factors to distinguish premature stop codons (PTCs) from normal stop codons in transcripts. Recently, emerging evidence has indicated that NMD factors are associated with neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability (ID). However, the mechanism in which these factors control embryonic brain development is not clear.
RESULT: We found that RBM8a is critical for proliferation and differentiation in cortical neural progenitor cells (NPCs). RBM8a is highly expressed in the subventricular zone (SVZ) of the early embryonic cortex, suggesting that RBM8a may play a role in regulating NPCs. RBM8a overexpression stimulates embryonic NPC proliferation and suppresses neuronal differentiation. Conversely, knockdown of RBM8a in the neocortex reduces NPC proliferation and promotes premature neuronal differentiation. Moreover, overexpression of RBM8a suppresses cell cycle exit and keeps cortical NPCs in a proliferative state. To uncover the underlying mechanisms of this phenotype, genome-wide RNAseq was used to identify potential downstream genes of RBM8a in the brain, which have been implicated in autism and neurodevelopmental disorders. Interestingly, autism and schizophrenia risk genes are highly represented in downstream transcripts of RBM8a. In addition, RBM8a regulates multiple alternative splicing genes and NMD targets that are implicated in ASD. Taken together, this data suggests a novel role of RBM8a in the regulation of neurodevelopment.
CONCLUSIONS: Our studies provide some insight into causes of mental illnesses and will facilitate the development of new therapeutic strategies for neurodevelopmental illnesses.

PMID: 26094033 [PubMed - as supplied by publisher]

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