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Fragile X Syndrome

Nicholas Zareifopoulos, Costas Papatheodoropoulos
The 5-HT7R is the most recently cloned serotonin receptor and thus one the least studied. Many drugs, experimental and in clinical use bind to 5-HT7 with high affinity, though their effects have yet to be clearly elucidated. Its physiological function, though not completely clear, is mostly associated with learning and memory, with both agonists and antagonists possessing subtle procognitive and promnesic properties. We consider it a promising area of research, though still in its infancy, which may one day lead to clinical benefits for patients with various afflictions characterised by cognitive dysfunction, particularily autism spectrum disorder, fragile X syndrome and Alzheimer's disease...
October 22, 2016: Neurobiology of Learning and Memory
Marta Pardo, Eleonore Beurel, Richard S Jope
Cotinine is the major metabolite of nicotine and has displayed some capacity for improving cognition in mouse models following chronic administration. We tested if acute cotinine treatment is capable of improving cognition in the mouse model of Fragile X syndrome, Fmr1(-/-) knockout mice, and if this is related to inhibition by cotinine treatment of glycogen synthase kinase-3β (GSK3β), which is abnormally active in Fmr1(-/-) mice. Acute cotinine treatment increased the inhibitory serine-phosphorylation of GSK3β and the activating phosphorylation of AKT, which can mediate serine-phosphorylation of GSK3β, in both wild-type and Fmr1(-/-) mouse hippocampus...
October 24, 2016: European Journal of Neuroscience
Sonia Merino, Nekane Ibarluzea, Hiart Maortua, Begoña Prieto, Idoia Rouco, Maria-Asunción López-Aríztegui, Maria-Isabel Tejada
Fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated primary ovarian insufficiency (FXPOI) are definitely related to the fragile X mental retardation 1 (FMR1) premutation (PM). Additional medical problems have also been associated with the PM, such as fibromyalgia, endocrine, and psychiatric disorders. To improve our understanding in the field, we reviewed all PM carriers and their reasons for any medical referrals from 104 fragile X families molecularly diagnosed in our laboratory and living in the Spanish Basque Country...
October 21, 2016: Genes
M I Alvarez-Mora, L Rodriguez-Revenga, I Madrigal, M Guitart-Mampel, G Garrabou, M Milà
Mitochondrial involvement plays an important role in neurodegenerative diseases. At least one-third of adult carriers of a FMR1 premutation (55-200 CGG repeats) are at risk of presenting an adult-onset neurodegenerative disorder known as fragile X-associated tremor/ataxia syndrome (FXTAS). In an attempt to provide new insights into the mechanisms involved in the pathogenesis of FXTAS, we characterized mitochondrial function and dynamics by the assessment of oxidative respiratory chain function, mitochondrial content, oxidative stress levels, and mitochondrial network complexity...
October 22, 2016: Molecular Neurobiology
Matthias Groh, Laura Oana Albulescu, Agnese Cristini, Natalia Gromak
R-loops comprise an RNA/DNA hybrid and displaced single-stranded DNA. They play crucial biological functions and are implicated in neurological diseases, including ataxias, amyotrophic lateral sclerosis, nucleotide expansion disorders (Friedreich ataxia, Fragile X syndrome) and cancer. Currently it is unclear which mechanisms cause R-loops structures to become pathogenic. The RNA/DNA helicase Senataxin (SETX) is one of the best characterised R-loop-binding factors in vivo. Mutations in SETX are linked to two neurodegenerative disorders: ataxia with oculomotor apraxia type 2 (AOA2) and amyotrophic lateral sclerosis type 4 (ALS4)...
October 19, 2016: Journal of Molecular Biology
Gordon X Wang, Stephen J Smith, Philippe Mourrain
The distribution of proteins within sub-synaptic compartments is an essential aspect of their neurological function. Current methodology such as electron microscopy (EM) and super-resolution imaging techniques can provide precise localization of proteins, but are often limited to a small number of one-time observations with narrow spatial and molecular coverage. The diversity of synaptic proteins and synapse types demands synapse analysis on a scale that is prohibitive with current methods. Here, we demonstrate SubSynMAP, a fast, multiplexed sub-synaptic protein analysis method using wide-field data from deconvolution array tomography (ATD)...
October 22, 2016: ELife
Nina Xie, He Gong, Joshua A Suhl, Pankaj Chopra, Tao Wang, Stephen T Warren
Fragile X syndrome (FXS) is a common cause of intellectual disability that is most often due to a CGG-repeat expansion mutation in the FMR1 gene that triggers epigenetic gene silencing. Epigenetic modifying drugs can only transiently and modestly induce FMR1 reactivation in the presence of the elongated CGG repeat. As a proof-of-principle, we excised the expanded CGG-repeat in both somatic cell hybrids containing the human fragile X chromosome and human FXS iPS cells using the CRISPR/Cas9 genome editing. We observed transcriptional reactivation in approximately 67% of the CRISPR cut hybrid colonies and in 20% of isolated human FXS iPSC colonies...
2016: PloS One
Amy Krans, Michael G Kearse, Peter K Todd
OBJECTIVE: Repeat associated non-AUG (RAN) translation drives production of toxic proteins from pathogenic repeat sequences in multiple untreatable neurodegenerative disorders. Fragile X-associated tremor/ataxia syndrome (FXTAS) is one such condition, resulting from a CGG trinucleotide repeat expansion in the 5' leader sequence of the FMR1 gene. RAN proteins from the CGG repeat accumulate in ubiquitinated inclusions in FXTAS patient brains and elicit toxicity. In addition to the CGG repeat, an antisense mRNA containing a CCG repeat is also transcribed from the FMR1 locus...
October 19, 2016: Annals of Neurology
Indhu-Shree Rajan-Babu, Samuel S Chong
Fragile X syndrome (FXS) is the most common monogenic cause of intellectual disability and autism. Molecular diagnostic testing of FXS and related disorders (fragile X-associated primary ovarian insufficiency (FXPOI) and fragile X-associated tremor/ataxia syndrome (FXTAS)) relies on a combination of polymerase chain reaction (PCR) and Southern blot (SB) for the fragile X mental retardation 1 (FMR1) CGG-repeat expansion and methylation analyses. Recent advancements in PCR-based technologies have enabled the characterization of the complete spectrum of CGG-repeat mutation, with or without methylation assessment, and, as a result, have reduced our reliance on the labor- and time-intensive SB, which is the gold standard FXS diagnostic test...
October 14, 2016: Genes
Jeremy Veenstra-VanderWeele, Edwin H Cook, Bryan H King, Peter Zarevics, Maryann Cherubini, Karen Walton-Bowen, Mark F Bear, Paul P Wang, Randall L Carpenter
Several lines of emerging data point to an imbalance between neuronal excitation and inhibition in at least a subgroup of individuals with autism spectrum disorder (ASD), including in those with fragile X syndrome (FXS), one of the most common genetic syndromes within ASD. In animal models of FXS and of ASD, GABA-B agonists have improved both brain and behavioral phenotypes, including social behavior. A phase 2 randomized, placebo-controlled, crossover trial found that the GABA-B agonist arbaclofen improved social avoidance symptoms in FXS...
October 17, 2016: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
Cyrus Vahdatpour, Adam H Dyer, Daniela Tropea
Insulin-Like Growth Factor 1 (IGF-1) is a neurotrophic polypeptide with crucial roles to play in Central Nervous System (CNS) growth, development and maturation. Following interrogation of the neurobiology underlying several neurodevelopmental disorders and Autism Spectrum Disorders (ASD), both recombinant IGF-1 (mecasermin) and related derivatives, such as (1-3)IGF-1, have emerged as potential therapeutic approaches. Clinical pilot studies and early reports have supported the safety/preliminary efficacy of IGF-1 and related compounds in the treatment of Rett Syndrome, with evidence mounting for its use in Phelan McDermid Syndrome and Fragile X Syndrome...
2016: Frontiers in Neuroscience
S S Hall, R P Barnett, K M Hustyi
BACKGROUND: A large proportion of boys with fragile X syndrome (FXS), the most common known inherited form of intellectual disability (ID), exhibit problem behaviours (e.g. aggression, self-injury, property destruction and stereotypy) that can negatively impact the health and safety of others as well as the individual concerned. However, data are limited concerning the relative prevalence, frequency and severity of problem behaviours exhibited by boys with FXS compared with those by boys with mixed-aetiology ID who also exhibit problem behaviours...
October 11, 2016: Journal of Intellectual Disability Research: JIDR
Ping Lu, Xiaolong Chen, Yun Feng, Qiao Zeng, Cizhong Jiang, Xianmin Zhu, Guoping Fan, Zhigang Xue
Fragile X syndrome (FXS) patients carry the expansion of over 200 CGG repeats at the promoter of fragile X mental retardation 1 (FMR1), leading to decreased or absent expression of its encoded fragile X mental retardation protein (FMRP). However, the global transcriptional alteration by FMRP deficiency has not been well characterized at single nucleotide resolution, i.e., RNA-seq. Here, we performed in-vitro neuronal differentiation of human induced pluripotent stem (iPS) cells that were derived from fibroblasts of a FXS patient (FXS-iPSC)...
October 11, 2016: Science China. Life Sciences
Rebecca Lyndsey Hardiman, Alison Bratt
Fragile X Syndrome (FXS) is characterised by features including anxiety and autistic-like behaviour, which led to early hypotheses that aberrant physiological arousal may underlie the behavioural phenotype. In line with this, several lines of evidence suggest that the hypothalamic-pituitary-adrenal (HPA) axis may be altered in the syndrome. This review collates evidence to determine the nature of HPA axis baseline activity and reactivity (as measured by glucocorticoid levels) differences in FXS, and its relationship to behaviour...
October 5, 2016: Physiology & Behavior
Ramona Alfaro Arenas, Jordi Rosell Andreo, Damián Heine Suñer
We report herein results of a study performed in the Balearic Islands which had the following goals: 1) Determine the proportion of pregnant or non-pregnant women planning pregnancy, who would choose to undergo a screening test for Fragile X Syndrome (FXS), if it is accompanied by the appropriate information; 2) Assess satisfaction and any increase in stress among women who participate in screening; 3) Collect epidemiological information about the incidence of the disease in our population; and 4) Collect demographic and health history data and assess participants' awareness of the disease...
October 7, 2016: Journal of Genetic Counseling
Yifan Zhou, Daman Kumari, Nicholas Sciascia, Karen Usdin
BACKGROUND: Fragile X syndrome (FXS), a common cause of intellectual disability and autism, results from the expansion of a CGG-repeat tract in the 5' untranslated region of the FMR1 gene to >200 repeats. Such expanded alleles, known as full mutation (FM) alleles, are epigenetically silenced in differentiated cells thus resulting in the loss of FMRP, a protein important for learning and memory. The timing of repeat expansion and FMR1 gene silencing is controversial. METHODS: We monitored the repeat size and methylation status of FMR1 alleles with expanded CGG repeats in patient-derived induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs) that were grown for extended period of time either as stem cells or differentiated into neurons...
2016: Molecular Autism
Chul-Yong Park, Jin Jea Sung, Sang-Hwi Choi, Dongjin R Lee, In-Hyun Park, Dong-Wook Kim
Genome engineering technology using engineered nucleases has been rapidly developing, enabling the efficient correction of simple mutations. However, the precise correction of structural variations (SVs) such as large inversions remains limited. Here we describe a detailed procedure for the modeling or correction of large chromosomal rearrangements and short nucleotide repeat expansions using engineered nucleases in human induced pluripotent stem cells (hiPSCs) from a healthy donor and patients with SVs. This protocol includes the delivery of engineered nucleases with no donor template to hiPSCs, and genotyping and derivation/characterization of gene-manipulated hiPSC clones...
November 2016: Nature Protocols
Clara D M van Karnebeek, Kristin Bowden, Elizabeth Berry-Kravis
BACKGROUND: Neurogenetic developmental conditions represent a heterogeneous group of rare inherited disorders with neurological manifestation during development. Treatments for these conditions have largely been supportive; however, a number of treatments are emerging which target the underlying physiology and offer great potential. Our aim was to present a state-of-the-art overview of the current and potential causal treatments available or under development for neurogenetic developmental conditions...
July 26, 2016: Pediatric Neurology
Yun Tae Hwang, Solange Mabel Aliaga, Marta Arpone, David Francis, Xin Li, Belinda Chong, Howard Robert Slater, Carolyn Rogers, Lesley Bretherton, Matthew Hunter, Robert Heard, David Eugeny Godler
CGG repeat expansion >200 within FMR1, termed full mutation (FM), has been associated with promoter methylation, consequent silencing of gene expression and fragile X syndrome (FXS)-a common cause of intellectual disability and co-morbid autism. Unmethylated premutation (55-199 repeats) and FM alleles have been associated with fragile X related tremor/ataxia syndrome (FXTAS), a late onset neurodegenerative disorder. Here we present a 33-year-old male with FXS, with white matter changes and progressive deterioration in gait with cerebellar signs consistent with probable FXTAS; there was no evidence of any other cerebellar pathology...
October 1, 2016: American Journal of Medical Genetics. Part A
Atefeh Entezari, Mahmoud Shekari Khaniani, Tayyeb Bahrami, Sima Mansoori Derakhshan, Hossein Darvish
Male carriers of an expansion of CGG alleles (with 55-200 CGG repeats) in the FMR1 gene are affected with Fragile X-associated tremor/ataxia syndrome (FXTAS). On the other hand, individuals with Parkinson's disease (PD) or Parkinsonism spectrum disorders may have some clinical features that overlap with FXTAS. To investigate the possible association between PD and FMR1 expanded alleles, we screened a total of 154 male PD patients and 190 gender- and age-matched healthy control subjects from Iran. Eleven intermediate allele carriers (7...
October 1, 2016: Neurological Sciences
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