EEG abnormalities and seizures in genetically diagnosed Fragile X syndrome

We describe the seizure and EEG characteristics in a population of children with known Fragile X. The medical records of 135 genetically confirmed FXS patients receiving care in a Fragile X clinic and their available EEG reports were reviewed. The mean age was 5.94 years old including 18 males and 1 female. The mean age was 4–9 years old with an age range of 15 months to 13 years old. Twenty-two patients (16.3%) in the series had parent-reported behavior suspicious of seizures. Sixteen patients (14.1%, 1 female) had at least one EEG recorded for evaluation of clinical events suspicious for seizure, and three patients (2.2%) had an EEG in the context of a polysomnography for diagnosing sleep apnea. The mean age at EEG evaluation was 6.0 years (standard deviation 3.8 years). EEG findings included slowing of background rhythm (n = 9) and epileptiform discharges (n = 7). Four patients had normal EEGs (n = 4). Six patients (4.4% of the sample population) were diagnosed with epilepsy by both clinical seizure semiology and documented EEG abnormalities. Thirteen patients (68.4% of total) had episodes of staring and behavioral arrest with no EEG correlate, indicating non-epileptic events. Of the eight patients who underwent a repeat EEG, five patients had showed normalization in the posterior dominant rhythm over time, two patients had unchanged findings and one patient had worsening of his EEG. Our data warrant further prospective validation.     

Fragile X syndrome associated with tic disorders

Movement disorders other than late onset tremor‐ataxia in association with fragile X syndrome, the most common identifiable cause of inherited mental retardation, seem to be rare. Here we describe five male patients from three unrelated families with fragile X syndrome that presented with motor and phonic tics. Clinically, 4 patients fulfilled diagnostic criteria for Gilles de la Tourette syndrome (GTS) while 1 patient would have been diagnosed with an adult onset tic disorder. However, in all patients onset of tics was considerably later than in typical GTS. Three patients had atypical tics and two patients reported waxing and waning of tic intensity over time. Four of the 5 patients showed clinical signs typical of fragile X syndrome, in particular dysmorphic features, learning difficulties and speech and language problems that required special treatment. All patients had co‐morbidities common to both GTS and fragile X syndrome. We suggest considering fragile X syndrome in GTS complicated by co‐morbidity with late onset of atypical tics, in particular when learning disability and dysmorphic features are present. © 2008 Movement Disorder Society     

Fragile X syndrome and cerebral perfusion abnormalities: single-photon emission computed tomographic study

Fragile X syndrome is an inherited disorder caused by a defective gene on the X chromosome. It is associated with developmental or behavioral symptoms and various degrees of mental retardation. Morphologic abnormalities and altered perfusion of various brain areas can underlie these functional disturbances. The aim of this study was to investigate the cerebral perfusion state in patients with fragile X syndrome using single-photon emission computed tomography (SPECT). Structural and functional assessment was also performed by magnetic resonance imaging (MRI) and electroencephalography (EEG). Eight boys with cytogenetically confirmed fragile X syndrome (mean age 8.8 +/- 4.4 years, range 5-18 years), were included. All patients had mental retardation, with a mean IQ of 58.9 +/- 8.8 (range 40-68), and additional neurobehavioral symptoms. SPECT revealed cerebral perfusion abnormalities in six patients (75%), most commonly in the frontoparietotemporal area and prominent in the right hemisphere. The SPECT and EEG findings were concordant: hypoperfused areas in SPECT corresponded to regions of persistent slow-wave paroxysms on EEG. On the other hand, cranial MRI was abnormal qualitatively only in two patients (25%) showing cerebellar and vermal hypoplasia and cerebral hemispheric asymmetry. Our results indicate that cerebral perfusion abnormalities, which are correlated with electrophysiologic findings but not necessarily with anatomic abnormalities, can underlie the pathogenesis of the clinical findings observed in fragile X syndrome.     

Fragile X syndrome

The physical, psychological, and cytogenetic characteristics of individuals with the Fragile X syndrome were reviewed. Prospects for therapy with folic acid, prenatal diagnosis, phenotype of heterozygotes for the marker X, and unresolved issues about the syndrome were discussed.     

Fragile X syndrome

Fragile X syndrome is the most important X-linked etiology of mental retardation and developmental disability currently known. Accumulating evidence also indicates that male and female carriers of the fragile X genetic abnormality demonstrate a relatively specific pattern of psychiatric disturbance. Fragile X males frequently manifest behaviors from the autistic spectrum whereas females show dysfunction in social interaction, thought processes, and affective regulation. In this review, an overview of the fragile X syndrome is presented with a focus on the occurrence of particular neuropsychiatric characteristics in males and females. Relevant data from recent genetic and neurobiological research is also described. The ability to study individuals with a specific genetic cause of psychopathology such as fragile X syndrome makes this condition of particular interest to biological psychiatry.     

脆性X综合征与癫痫

脆性X综合征(fragile X syndrome,FXS)是一种最常见的遗传性智力障碍.这种智力障碍疾病主要是由于脆性X智力低下蛋白(fragile X mental retardation protein,FMRP)的缺失引起.FMRP是一种RNA结合蛋白,通过调节与其结合的信使RNA的翻译而调节神经元内的信号传导.很多FXS病人表现出较高的癫痫发作易感性.癫痫是一种慢性神经系统疾病.它的主要症状是反复的癫痫发作.癫痫发作是由大脑神经元的异常高兴奋性和同步放电引起的.FMEP缺失引起的神经元形态异常和神经元内信号传导的异常均可导致癫痫发作.本文结合在FXS和癫痫病两方面上取得研究结果综合分析,探讨FXS病人癫痫高易感性的发病机理,并对其他智力障碍疾病中的癫痫高易感性的机制的研究做一展望.     

Fragile X syndrome: assessment and treatment implications

Fragile X syndrome (FraX) is the most common known cause of inherited mental impairment. FMR1 gene mutations, the cause of FraX, lead to reduced expression of FMR1 protein and an increased risk for a particular profile of cognitive, behavioral, and emotional dysfunction. The study of individuals with FraX provides a unique window of understanding into important disorders such as autism, social phobia, cognitive disability, and depression. This review highlights the typical phenotypic features of individuals with FraX, discussing the apparent strengths and weaknesses in intellectual functioning, as evidenced from longitudinal follow-up studies. It also discusses recent neuroanatomic findings that may pave the way for more focused disease-specific pharmacologic and behavioral interventions. This article describes the results of recent medication trials designed to target symptoms associated with FraX. It also describes some recent behavioral interventions that were conducted in our laboratory.     

Fragile X syndrome: genetic predisposition to psychopathology

Fragile X syndrome is a newly recognized X-linked disorder which has been associated with a high prevalence of psychiatric disturbance, particularly attention deficit disorder and autism. The present study involved the neuropsychiatric evaluation of 14 males with the disorder who were between the ages of 3 to 27 years. Pervasive hyperactivity, impulsivity, and attentional deficits were found among all of the subjects, while a significant degree of anxiety was manifested by more than half. Although the majority of subjects exhibited poor eye contact, atypical speech and language functioning, and stereotyped behavior, only one met DSM-III diagnostic criteria for a persistent pervasive developmental disorder. Gaze aversion, noted among half of the subjects, was attributed to underlying anxiety rather than to autistic social dysfunction because of the otherwise socially engaged and affectionate behavior exhibited by the subjects. Failure to make this distinction in the context of cognitive and linguistic impairments associated with fragile X syndrome may account for the high rates of autism reported by other investigators.     

Newborn screening in Fragile X syndrome

Background : Screening for the FMR1 mutations has been a topic of considerable discussion since the FMR1 gene was identified. However, Fragile X has not been recommended for newborn screening mainly because of the lack of an accurate screening test and of data on potential benefits. We have recently developed an improved Polymerase Chain Reaction (PCR) method for the identification of premutation and full mutation alleles for the FMR1 gene. Method : The method is inexpensive, accurate and quick and can be performed on a number of sample templates including, importantly, blood spots. We have applied this method for international screening. Specifically, we have screened 5267 anonymous blood spot samples from newborn males from the centre‐northwest region of Spain. We have also used this technology to a pilot ‘high risk’ screening program of individuals with autism and/or intellectual disabilities and family members of a proband with fragile X initiated in Guatemala. This project is a prototype for future screening endeavours. Results : One important outcome from this study is that the frequency of premutation alleles (1 per 250) appears to be higher than previously reported. This is of importance, especially in view of the different phenotypic involvement observed in carriers of premutation alleles, including neurological problems such as FXTAS. Here, we present data on the frequency of premutation/full alleles found in this population and their size distribution. Conclusion : This project is a prototype for future screening endeavours. Results from our pilot program in both Spain and Guatemala will lend strong support for implementing this technology for rapid screening to a much larger scale population screening.     

Fragile X syndrome: the GABAergic system and circuit dysfunction

Fragile X syndrome (FXS) is a neurodevelopmental disorder characterized by intellectual disability, sensory hypersensitivity, and high incidences of autism spectrum disorders and epilepsy. These phenotypes are suggestive of defects in neural circuit development and imbalances in excitatory glutamatergic and inhibitory GABAergic neurotransmission. While alterations in excitatory synapse function and plasticity are well-established in Fmr1 knockout (KO) mouse models of FXS, a number of recent electrophysiological and molecular studies now identify prominent defects in inhibitory GABAergic transmission in behaviorally relevant forebrain regions such as the amygdala, cortex, and hippocampus. In this review, we summarize evidence for GABAergic system dysfunction in FXS patients and Fmr1 KO mouse models alike. We then discuss some of the known developmental roles of GABAergic signaling, as well as the development and refinement of GABAergic synapses as a framework for understanding potential causes of mature circuit dysfunction. Finally, we highlight the GABAergic system as a relevant target for the treatment of FXS.     

Fragile X syndrome, DSM-III-R, and autism

Although reports of autistic behavior in fragile X males have been published for 8 years, there is little information about specific behaviors shown by fragile X males that are suggestive of the diagnosis of autism. The new diagnostic criteria for autistic disorder contained in the DSM-III-R provided the opportunity for more closely investigating the topography of autistic behavior in 17 fragile X males and the effects of age and IQ on its occurrence. The criteria most frequently met by these subjects were related to deficits in social interaction with peers, abnormalities in verbal and nonverbal communication, stereotypic motor behavior, and unusual responses to sensory stimuli. Fragile X subjects did not frequently show abnormalities in attachment behaviors and reciprocal interaction with caregivers. There were no discernable age or IQ effects. The importance and implications of these findings are discussed and the need for greater exploration of autism "subtypes" is emphasized.     

Williams syndrome: Serotonin's association with developmental disabilities

Reiss et al. (1985) described two autistic children with the Williams syndrome, a dysmorphic developmental syndrome of unknown cause. Both children also showed elevated blood serotonin levels. The present report describes two prepubescent females with the characteristic features of Williams syndrome, who are not autistic and who have blood serotonin levels within the normal range. These findings suggest that further study of developmental disorders that coexist with autism may help clarify the relationship between autism and putative biological markers such as hyperserotonemia.The authors thank Arthur Yuwiler, for his support and assistance in this study. We also thank the patients and their families for their cooperation.     

Developmental Gerstmann syndrome without aphasia in Fragile X syndrome

Considerable controversy surrounds Gerstmann's syndrome, with some authors questioning its localizing significance, and others doubting its existence as a distinct entity. This literature is reviewed, and a case is presented of a young boy with Fragile X syndrome who showed all five symptoms of the developmental Gerstmann syndrome. He was one of a group of individuals found to be cytogenetically positive for Fragile X syndrome, who were observed to possess three or more of Gerstmann's symptons in the complete absence of aphasic disorder.