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1.  Fragile X Syndrome and Targeted Treatment Trials 
Work in recent years has revealed an abundance of possible new treatment targets for fragile X syndrome (FXS). The use of animal models, including the fragile X knockout mouse which manifests a phenotype very similar to FXS in humans, has resulted in great strides in this direction of research. The lack of Fragile X Mental Retardation Protein (FMRP) in FXS causes dysregulation and usually overexpression of a number of its target genes, which can cause imbalances of neurotransmission and deficits in synaptic plasticity. The use of metabotropic glutamate receptor (mGluR) blockers and gamma amino-butyric acid (GABA) agonists have been shown to be efficacious in reversing cellular and behavioral phenotypes, and restoring proper brain connectivity in the mouse and fly models. Proposed new pharmacological treatments and educational interventions are discussed in this chapter. In combination, these various targeted treatments show promising preliminary results in mitigating or even reversing the neurobiological abnormalities caused by loss of FMRP, with possible translational applications to other neurodevelopmental disorders including autism.
doi:10.1007/978-3-642-21649-7_17
PMCID: PMC4114775  PMID: 22009360
2.  Increased prevalence of seizures in boys who were probands with the FMR1 premutation and co-morbid autism spectrum disorder 
Human genetics  2011;131(4):581-589.
Seizures are a common co-occurring condition in those with fragile X syndrome (FXS), and in those with idiopathic autism spectrum disorder (ASD). Seizures are also associated with ASD in those with FXS. However, little is known about the rate of seizures and how commonly these problems co-occur with ASD in boys with the FMR1 premutation. We, therefore, determined the prevalence of seizures and ASD in boys with the FMR1 permutation compared with their sibling counterparts and population prevalence estimates. Fifty premutation boys who presented as clinical probands (N = 25), or non-probands (identified by cascade testing after the proband was found) (N = 25), and 32 non-carrier controls were enrolled. History of seizures was documented and ASD was diagnosed by standardized measures followed by a team consensus of ASD diagnosis. Seizures (28%) and ASD (68%) were more prevalent in probands compared with non-probands (0 and 28%), controls (0 and 0%), and population estimates (1 and 1.7%). Seizures occurred more frequently in those with the premutation and co-morbid ASD particularly in probands compared with those with the premutation alone (25 vs. 3.85%, p = 0.045). Although cognitive and adaptive functioning in non-probands were similar to controls, non-probands were more likely to meet the diagnosis of ASD than controls (28 vs. 0%, p < 0.0001). In conclusion, seizures were relatively more common in premutation carriers who presented clinically as probands of the family and seizures were commonly associated with ASD in these boys. Therefore, boys with the premutation, particularly if they are probands should be assessed carefully for both ASD and seizures.
doi:10.1007/s00439-011-1106-6
PMCID: PMC4105134  PMID: 22001913
3.  Sertraline May Improve Language Developmental Trajectory in Young Children with Fragile X Syndrome: A Retrospective Chart Review 
Autism Research and Treatment  2012;2012:104317.
Young children with fragile X syndrome (FXS) often experience anxiety, irritability, and hyperactivity related to sensory hyperarousal. However, there are no medication recommendations with documented efficacy for children under 5 years old of age with FXS. We examined data through a chart review for 45 children with FXS, 12–50 months old, using the Mullen Scales of Early Learning (MSEL) for baseline and longitudinal assessments. All children had clinical level of anxiety, language delays based on MSEL scores, and similar early learning composite (ELC) scores at their first visit to our clinic. Incidence of autism spectrum disorder (ASD) was similar in both groups. There were 11 children who were treated with sertraline, and these patients were retrospectively compared to 34 children who were not treated with sertraline by chart review. The baseline assessments were done at ages ranging from 18 to 44 months (mean 26.9, SD 7.99) and from 12 to 50 months (mean 29.94, SD 8.64) for treated and not treated groups, respectively. Mean rate of improvement in both expressive and receptive language development was significantly higher in the group who was treated with sertraline (P < 0.0001 and P = 0.0071, resp.). This data supports the need for a controlled trial of sertraline treatment in young children with FXS.
doi:10.1155/2012/104317
PMCID: PMC3420618  PMID: 22934167
4.  FMR1 premutation and full mutation molecular mechanisms related to autism 
Fragile X syndrome (FXS) is caused by an expanded CGG repeat (>200 repeats) in the 5′ un-translated portion of the fragile X mental retardation 1 gene (FMR1) leading to a deficiency or absence of the FMR1 protein (FMRP). FMRP is an RNA-binding protein that regulates the translation of a number of other genes that are important for synaptic development and plasticity. Furthermore, many of these genes, when mutated, have been linked to autism in the general population, which may explain the high comorbidity that exists between FXS and autism spectrum disorders (ASD). Additionally, premutation repeat expansions (55 to 200 CGG repeats) may also give rise to ASD through a different molecular mechanism that involves a direct toxic effect of FMR1 mRNA. It is believed that RNA toxicity underlies much of the premutation-related involvement, including developmental concerns like autism, as well as neurodegenerative issues with aging such as the fragile X-associated tremor ataxia syndrome (FXTAS). RNA toxicity can also lead to mitochondrial dysfunction, which is common in older premutation carriers both with and without FXTAS. Many of the problems with cellular dysregulation in both premutation and full mutation neurons also parallel the cellular abnormalities that have been documented in idiopathic autism. Research regarding dysregulation of neurotransmitter systems caused by the lack of FMRP in FXS, including metabotropic glutamate receptor 1/5 (mGluR1/5) pathway and GABA pathways, has led to new targeted treatments for FXS. Preliminary evidence suggests that these new targeted treatments will also be beneficial in non-fragile X forms of autism.
doi:10.1007/s11689-011-9084-5
PMCID: PMC3261276  PMID: 21617890
Fragile X; Autism; ASD; Premutation; mGluR5 antagonist; Molecular background of fragile X; Molecular background of autism; Targeted treatments; MicroRNA; miRNA; Mitochondrial abnormalities
5.  Neuropathologic features in the hippocampus and cerebellum of three older men with fragile X syndrome 
Molecular Autism  2011;2:2.
Background
Fragile X syndrome (FXS) is the most common inherited form of intellectual disability, and is the most common single-gene disorder known to be associated with autism. Despite recent advances in functional neuroimaging and our understanding of the molecular pathogenesis, only limited neuropathologic information on FXS is available.
Methods
Neuropathologic examinations were performed on post-mortem brain tissue from three older men (aged 57, 64 and 78 years) who had received a clinical or genetic diagnosis of FXS. In each case, physical and cognitive features were typical of FXS, and one man was also diagnosed with autism. Guided by reports of clinical and neuroimaging abnormalities of the limbic system and cerebellum of individuals with FXS, the current analysis focused on neuropathologic features present in the hippocampus and the cerebellar vermis.
Results
Histologic and immunologic staining revealed abnormalities in both the hippocampus and cerebellar vermis. Focal thickening of hippocampal CA1 and irregularities in the appearance of the dentate gyrus were identified. All lobules of the cerebellar vermis and the lateral cortex of the posterior lobe of the cerebellum had decreased numbers of Purkinje cells, which were occasionally misplaced, and often lacked proper orientation. There were mild, albeit excessive, undulations of the internal granular cell layer, with patchy foliar white matter axonal and astrocytic abnormalities. Quantitative analysis documented panfoliar atrophy of both the anterior and posterior lobes of the vermis, with preferential atrophy of the posterior lobule (VI to VII) compared with age-matched normal controls.
Conclusions
Significant morphologic changes in the hippocampus and cerebellum in three adult men with FXS were identified. This pattern of pathologic features supports the idea that primary defects in neuronal migration, neurogenesis and aging may underlie the neuropathology reported in FXS.
doi:10.1186/2040-2392-2-2
PMCID: PMC3045897  PMID: 21303513

Results 1-5 (5)