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Biomedical subjects

R J Hagerman

Publications and source records attributed to R J Hagerman.

At least 19 recordsLinked to original sources
PubMed2006

Prevalence of FMR1 repeat expansions in movement disorders. A systematic review.

We reviewed prevalence rates of fragile X mental retardation gene (FMR1) repeat expansions in movement disorder populations. Inclusion criteria included published epidemiological studies from systematic searches of Medline, Pubmed, Cochrane Databases and Web Science. Thirteen cross-sectional studies were carried out between 2003 and 2005. Subjects with ataxia showed higher than expected rates while those with essential tremor and parkinsonism showed lower rates. The heterogeneous design of the studies, inclusion criteria and mean age of subjects may have led to underestimation of FMR1 repeat expansion prevalence rates.

Cross-Sectional Studies↗
PubMed2005

Neuropathology of fragile X-associated tremor/ataxia syndrome (FXTAS).

Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder that affects carriers, principally males, of premutation alleles (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene. Clinical features of FXTAS include progressive intention tremor and gait ataxia, accompanied by characteristic white matter abnormalities on MRI. The neuropathological hallmark of FXTAS is an intranuclear inclusion, present in both neurons and astrocytes throughout the CNS. Prior to the current work, the nature of the associations between inclusion loads and molecular measures (e.g. CGG repeat) was not defined. Post-mortem brain and spinal cord tissue has been examined for gross and microscopic pathology in a series of 11 FXTAS cases (males, age 67-87 years at the time of death). Quantitative counts of inclusion numbers were performed in various brain regions in both neurons and astrocytes. Inclusion counts were compared with specific molecular (CGG repeat, FMR1 mRNA level) and clinical (age of onset, age of death) parameters. In the current series, the three most prominent neuropathological characteristics are (i) significant cerebral and cerebellar white matter disease, (ii) associated astrocytic pathology with dramatically enlarged inclusion-bearing astrocytes prominent in cerebral white matter and (iii) the presence of intranuclear inclusions in both brain and spinal cord. The pattern of white matter pathology is distinct from that associated with hypertensive vascular disease and other diseases of white matter. Spongiosis was present in the middle cerebellar peduncles in seven of the eight cases in which those tissues were available for study. There is inclusion formation in cranial nerve nucleus XII and in autonomic neurons of the spinal cord. The most striking finding is the highly significant association between the number of CGG repeats and the numbers of intranuclear inclusions in both neurons and astrocytes, indicating that the CGG repeat is a powerful predictor of neurological involvement in males, both clinically (age of death) and neuropathologically (number of inclusions).

Age of Onset↗
PubMed2005

Protein composition of the intranuclear inclusions of FXTAS.

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder caused by premutation expansions (55-200 CGG repeats) in the fragile X mental retardation 1 (FMR1) gene. The pathologic hallmark of FXTAS is the ubiquitin-positive intranuclear inclusion found in neurons and astrocytes in broad distribution throughout the brain. The pathogenesis of FXTAS is likely to involve an RNA toxic gain-of-function mechanism, and the FMR1 mRNA has recently been identified within the inclusions. However, little is known about the proteins that mediate the abnormal cellular response to the expanded CGG repeat allele. As one approach to identify the protein mediators, we have endeavoured to define the protein complement of the inclusion itself. Fluorescence-activated flow-based methods have been developed for the efficient purification of inclusions from the post-mortem brain tissue of FXTAS patients. Mass spectrometric analysis of the entire protein complement of the isolated inclusions, combined with immunohistochemical analysis of both isolated nuclei and tissue sections, has been used to identify inclusion-associated proteins. More than 20 inclusion-associated proteins have been identified on the basis of combined immunohistochemical and mass spectrometric analysis, including a number of neurofilaments and lamin A/C. There is no dominant protein species in the inclusions, and ubiquitinated proteins represent only a minor component; thus, inclusion formation is not likely to reflect a breakdown in proteasomal degradation of nuclear proteins. The list of proteins includes at least two RNA binding proteins, heterogeneous nuclear ribonucleoprotein A2 and muscle blind-like protein 1, which are possible mediators of the RNA gain-of-function in FXTAS.

Aged↗
PubMed2005

Initial diagnoses given to persons with the fragile X associated tremor/ataxia syndrome (FXTAS).

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a newly described disorder that occurs in premutation carriers of the fragile X mental retardation 1 (FMR1) gene. Fifty-six patients with FXTAS were given 98 prior diagnoses: most were in the categories of parkinsonism, tremor, ataxia, dementia, or stroke. Data from this study and others were used to develop guidelines for FMR1 diagnostic testing for FXTAS.

Age Factors↗
PubMed2004

Fragile-X-associated tremor/ataxia syndrome (FXTAS) in females with the FMR1 premutation.

We describe five female carriers of the FMR1 premutation who presented with symptoms of tremor and ataxia and who received a diagnosis of definite or probable fragile-X-associated tremor/ataxia syndrome (FXTAS). Unlike their male counterparts with FXTAS, none of the women had dementia. Females had not been reported in previous studies of FXTAS, suggesting that they may be relatively protected from this disorder. Brain tissue was available from one of the five subjects, a women who died at age 85 years; microscopic examination revealed intranuclear neuronal and astrocytic inclusions, in accord with the findings previously reported in males with FXTAS. The work-up of families with the FMR1 mutation should include questions regarding neurological symptoms in both older male and female carriers, with the expectation that females may also manifest the symptoms of FXTAS, although more subtly and less often than their male counterparts.

Adult↗
PubMed2004

Aging in individuals with the FMR1 mutation.

Individuals with fragile X mental retardation 1 (FMR1) premutation (55 to 200 CGG repeats) are typically unaffected by fragile X syndrome. However, a subgroup of older males with the premutation have developed a neurological syndrome, which usually begins between 50 and 70 years and is associated with a progressive intention tremor and/or ataxia manifested by balance problems, frequent falling, and Parkinsonian symptoms, such as masked facies, intermittent resting tremor, and mild rigidity. This finding has been termed the fragile X-associated tremor/ataxia syndrome (FXTAS) and has brought focus to the aging process in individuals with the FMR1 mutation. The premutation is associated with elevated messenger RNA levels leading to the formation of intranuclear inclusions in neurons and astrocytes associated with FXTAS. This review is a summary of our experience with FXTAS in male carriers of the premutation.

Aged↗
PubMed2003

Effect of fragile X status categories and FMRP deficits on cognitive profiles estimated by robust pedigree analysis.

The effect of the fragile X pre-mutation and full mutation categories, and FMRP deficits in these categories, on neurocognitive status, have been assessed in fragile X individuals from 144 extended families, which included fragile X individuals, as well as their non-fragile X relatives. Neuropsychological status was assessed by the Wechsler summary and subtest test scores. A modification of the maximum likelihood estimators for pedigree data that is resistant to outliers was used to analyze the data. The results have demonstrated the effect of large expansions of CGG repeat in the FMR1 (fragile X mental retardation 1) gene (full mutation) in decreasing full scale IQ (FSIQ), as well as several FSIQ-adjusted subtest scores in the performance domain. Moreover, the results have demonstrated significant cognitive deficits in male individuals with pre-mutation. FMRP depletion correlates strongly with neurocognitive status in the full mutation subjects. Evidence for the effect of FMRP in smaller expansions (pre-mutation) in reducing FSIQ, Performance and Verbal scores, as well as subtest scores in males, has also been obtained. The results are also suggestive of factors other than FMRP deficit which may determine some specific cognitive deficits in fragile X pre-mutation carriers. Genetic variance estimated from the models accounts for less than half of the total variance in FSIQ, and it varies widely between individual Wechsler subtests.

Female↗
PubMed2003

Genetic and clinical characterization of patients with an interstitial duplication 15q11-q13, emphasizing behavioral phenotype and response to treatment.

The clinical significance of an interstitial duplication of (15)(q11-q13) remains unclear and controversial. The reported phenotypes vary widely and appear to be influenced by the parent of origin of the duplication. Aside from cases of dup(15) reported with autism, the behavioral phenotype of individuals with dup(15) has not been described. We present three families, two with intrachromosomal duplication (15)(q11-q13) ascertained because of developmental delay in a relative. Two families show clear evidence of multigenerational maternal inheritance. The individuals discussed in this paper have minor anomalies and developmental delays. In addition, we describe a behavioral phenotype which often includes attention deficit hyperactivity disorder (ADHD) and autistic spectrum disorder. Responses to medications used to manage these behaviors are also described, including a positive response to methylphenidate and a poor response to fluoxetine. The duplication in each presenting individual, and available family members, was investigated utilizing cytogenetic and molecular techniques including high resolution cytogenetics, fluorescence in situ hybridization (FISH), DNA methylation studies, and quantitative fluorescence PCR. High resolution cytogenetic techniques alone missed some cases, demonstrating the need to confirm results with other methods.

Child↗
PubMed2003

Relationship of deficits of FMR1 gene specific protein with physical phenotype of fragile X males and females in pedigrees: a new perspective.

The effect of deficit of the FMR1-gene product (FMRP) on physical phenotype was investigated using a robust modification of the maximum likelihood estimators for pedigree data. The approach is a powerful method of examining genotype-phenotype relationships because it adjusts for intra-familial variation, and the robust modification allows violation of distributional assumptions in the data to be overcome by objectively down-weighting unusual observations. The data on 19 age- or height-adjusted physical measures including head, trunk and limb measures and height and weight from 110 extended fragile X families (including 185 fragile X males and females and 120 normal relatives) were related to the FMRP levels assessed in peripheral blood lymphocytes. A significant interaction between FMRP and age was also included in the models for some measures. The results have demonstrated a linear effect of progressively reducing levels of FMRP on the values of a majority of physical measures considered in the study. The most evident effect of FMRP deficit in sexes combined was in decreasing body height and limb length, and in increasing head height and the degree of connective tissue involvement (measured by the middle finger extension angle). Heritability estimated from the complex FMRP models showed the highest values for height and limb length, and the lowest for weight, finger extension angle and some facial measures. On the basis of the present data, a possible mechanism by which the FMRP deficit impacts physical phenotype is discussed.

Adolescent↗
PubMed2003

A cerebellar tremor/ataxia syndrome among fragile X premutation carriers.

Fragile X syndrome is a neurodevelopmental disorder that is not known to have any progressive neurological sequelae in adulthood. However, a neurological condition involving intention tremor, ataxia, and cognitive decline has recently been identified among older male carriers of premutation alleles of the FMR1 gene. This condition is clinically distinct from fragile X syndrome and arises through a different molecular mechanism involving the same gene (FMR1). Characteristic findings on magnetic resonance imaging include cerebral and cerebellar volume loss and altered signal intensities of the middle cerebellar peduncles. A striking feature of this fragile X-associated tremor/ataxia syndrome is the presence of ubiquitin-positive neuronal and astroglial intranuclear inclusions. Unlike the CAG repeat expansion diseases, which lead to altered protein products, there is no known protein abnormality among FMR1 premutation carriers. Thus, inclusion formation may reflect a gain-of-function effect of the FMR1 mRNA or the CGG repeat itself. Finally, since this syndrome may represent one of the more common single-gene causes of tremor, ataxia, and dementia among older males, FMR1 DNA testing should be considered when evaluating adult patients with tremor/ataxia.

Cerebellar Ataxia↗
PubMed2002

Neuronal intranuclear inclusions in a new cerebellar tremor/ataxia syndrome among fragile X carriers.

A neurological syndrome involving progressive action tremor with ataxia, cognitive decline and generalized brain atrophy has been described recently in some adult males with pre-mutation alleles of the fragile X syndrome (FXS) fragile X mental retardation gene (FMR1). Neurohistological studies have now been performed on the brains of four elderly premutation carriers, not reported previously, who displayed the neurological phenotype. Eosinophilic, intranuclear inclusions were present in both neuronal and astrocytic nuclei of the cortex in all four individuals. Systematic analysis of the brains of two of these carriers demonstrated the presence of the intranuclear inclusions throughout the cerebrum and brainstem, being most numerous in the hippocampal formation. The cerebellum displayed marked dropout of Purkinje cells, Purkinje axonal torpedoes and Bergmann gliosis. Intranuclear inclusions were absent from Purkinje cells, although they were present in a small number of neurones in the dentate nucleus and diffusely in cerebellar astrocytes. The presence of inclusions in the brains of all four FXS carriers with the neurological findings provides further support for a unique clinical entity associated with pre-mutation FMR1 alleles. The origin of the inclusions is unknown, although elevated FMR1 mRNA levels in these pre-mutation carriers may lead to the neuropathological changes.

Aged↗
PubMed2001

Auditory evoked magnetic fields in adults with fragile X syndrome.

Hyper-reactivity and anxiety to sensory stimuli have been described in patients with fragile X syndrome (FXS), and may be related to abnormal processing in afferent sensory pathways. We used magnetoencephalography (MEG) to measure auditory responses to pure tones in 11 adults with FXS and 11 non-FXS subjects. The amplitude for the N100m auditory evoked field component was significantly higher for patients with FXS than for subjects. FXS subjects also had less lateralized N100m anterior-posterior dipole locations. These data may suggest that more neurons are activated by acoustic stimuli in FXS, consistent with subjective experience of increased stimulus intensity. Anomalous cerebral lateralization may suggest an early critical window for effects on neocortical development of the fragile X mental retardation protein (FMRP) produced by the FMR1 gene in individuals with FXS.

Adult↗
PubMed2001

Intention tremor, parkinsonism, and generalized brain atrophy in male carriers of fragile X.

The authors report five elderly men with the fragile X premutation who had a progressive action tremor associated with executive function deficits and generalized brain atrophy. These individuals had elevated fragile X mental retardation 1 gene (FMR1) messenger RNA and normal or borderline levels of FMR1 protein. The authors propose that elevations of FMR1 messenger RNA may be causative for a neurodegenerative syndrome in a subgroup of elderly men with the FMR1 premutation.

Aged↗
PubMed2001

Sensory modulation dysfunction in children with attention-deficit-hyperactivity disorder.

This study investigates the presence of sensory modulation dysfunction (SMD) among children with attention-deficit-hyperactivity disorder (ADHD). Twenty-six children with ADHD (mean age 8.3 years, 18 males, 8 females), and 30 typically developing children (mean age 8.2 years, 21 males, 9 females) were tested using a laboratory procedure that gauges responses to repeated sensory stimulation by measuring electrodermal reactivity (EDR). Parental report measures of limitations in sensory, emotional, and attentional dimensions were administered using the Short Sensory Profile, the Leiter International Performance Scale-Revised, Parent Rating subscales, and the Child Behavior Checklist (CBCL). Compared to the typical sample, the children with ADHD displayed greater abnormalities in sensory modulation on both physiological and parent-report measures. The children with ADHD also displayed more variability in responses. Within the group with ADHD, levels of SMD were highly correlated with measures of psychopathology on the CBCL. Implications of findings relate to the importance of considering sensory processing abilities in a subgroup of children with ADHD.

Adolescent↗
PubMed2001

A majority of fragile X males with methylated, full mutation alleles have significant levels of FMR1 messenger RNA.

FMR1 mRNA levels were determined in peripheral blood leucocytes for 48 fragile X males with methylated, full mutation alleles that are resistant to cleavage by methylation sensitive enzymes. Using quantitative (fluorescence) RT-PCR, we observed that more than half of these males produce FMR1 mRNA, with some mRNA levels approaching those found in normal subjects. In none of the samples analysed was there any evidence of premutation alleles. These results suggest that the assumed relationship between enzyme resistance and FMR1 gene silencing may not be generally valid. Despite the presence of FMR1 mRNA in some subjects, no FMRP production was detected by either immunocytochemistry or western blotting. The low/absent FMRP levels are probably a reflection of a post-trancriptional effect such as a defect in translation.

Alleles↗
PubMed2001

Profile of cognitive functioning in women with the fragile X mutation.

Two studies tested the specificity of the neurocognitive profile of women with fragile X syndrome (FXS). First, women with an FXS full mutation were compared with women with a premutation and women without FXS who grew up in FXS families. Women with FXS had a significantly lower IQ than the other groups, and analyses of subtest profiles showed they had a relative weakness on Arithmetic and strength on Picture Completion. Women with FXS performed worse than the other groups on executive function, spatial ability, and visual memory. Next, women with FXS were compared with women without FXS matched on age and IQ. A similar IQ profile was found, but women with FXS were worse than controls only on executive function. The authors also examined which neurocognitive indices were related to the underlying biology of the disorder. Overall, the results indicated that executive rather than visuospatial deficits were primary in the neurocognitive profile of FXS.

Adolescent↗