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Tassanakijpanich N, Cohen J, Cohen R, Srivatsa UN, Hagerman RJ. Cardiovascular Problems in the Fragile X Premutation. Front Genet 2020; 11:586910. [PMID: 33133171 PMCID: PMC7578382 DOI: 10.3389/fgene.2020.586910] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 09/21/2020] [Indexed: 12/12/2022] Open
Abstract
There is a dearth of information about cardiovascular problems in fragile X premutation carriers who have 55–200 CGG repeats in fragile X mental retardation 1 (FMR1) gene. The FMR1 expansion in the premutation range leads to toxic RNA gain-of-function resulting in cellular dysregulation. The mechanism of RNA toxicity underlies all of the premutation disorders including fragile X-associated tremor/ataxia syndrome, fragile X-associated primary ovarian insufficiency, and fragile X-associated neuropsychiatric disorder. Cardiovascular problems particularly autonomic dysfunction, hypertension, and cardiac arrhythmias are not uncommon in premutation carriers. Some arterial problems and valvular heart diseases have also been reported. This article reviews cardiovascular problems in premutation carriers and discusses possible contributing mechanisms including RNA toxicity and mild fragile X mental retardation protein deficiency. Further research studies are needed in order to prove a direct association of the cardiovascular problems in fragile X premutation carriers because such knowledge will lead to better preventative treatment.
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Affiliation(s)
- Nattaporn Tassanakijpanich
- UC Davis MIND Institute, UC Davis Health, Sacramento, CA, United States.,Department of Pediatrics, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
| | - Jonathan Cohen
- Fragile X Alliance Clinic, Genetic Clinics Australia, Melbourne, VIC, Australia
| | - Rashelle Cohen
- Fragile X Alliance Clinic, Genetic Clinics Australia, Melbourne, VIC, Australia
| | - Uma N Srivatsa
- Division of Cardiovascular Medicine, Department of Internal Medicine, UC Davis Medical Center, Sacramento, CA, United States
| | - Randi J Hagerman
- UC Davis MIND Institute, UC Davis Health, Sacramento, CA, United States.,Department of Pediatrics, University of California, Davis, Davis, School of Medicine, Sacramento, CA, United States
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Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS): Pathophysiology and Clinical Implications. Int J Mol Sci 2020; 21:ijms21124391. [PMID: 32575683 PMCID: PMC7352421 DOI: 10.3390/ijms21124391] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/23/2020] [Accepted: 05/28/2020] [Indexed: 02/06/2023] Open
Abstract
The fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder seen in older premutation (55-200 CGG repeats) carriers of FMR1. The premutation has excessive levels of FMR1 mRNA that lead to toxicity and mitochondrial dysfunction. The clinical features usually begin in the 60 s with an action or intention tremor followed by cerebellar ataxia, although 20% have only ataxia. MRI features include brain atrophy and white matter disease, especially in the middle cerebellar peduncles, periventricular areas, and splenium of the corpus callosum. Neurocognitive problems include memory and executive function deficits, although 50% of males can develop dementia. Females can be less affected by FXTAS because of a second X chromosome that does not carry the premutation. Approximately 40% of males and 16% of female carriers develop FXTAS. Since the premutation can occur in less than 1 in 200 women and 1 in 400 men, the FXTAS diagnosis should be considered in patients that present with tremor, ataxia, parkinsonian symptoms, neuropathy, and psychiatric problems. If a family history of a fragile X mutation is known, then FMR1 DNA testing is essential in patients with these symptoms.
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Small fiber neuropathy in a woman with fragile X-associated tremor/ataxia syndrome (FXTAS). J Neurol 2014; 262:226-7. [DOI: 10.1007/s00415-014-7597-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/22/2014] [Accepted: 11/24/2014] [Indexed: 11/26/2022]
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Hall DA, Birch RC, Anheim M, Jønch AE, Pintado E, O'Keefe J, Trollor JN, Stebbins GT, Hagerman RJ, Fahn S, Berry-Kravis E, Leehey MA. Emerging topics in FXTAS. J Neurodev Disord 2014; 6:31. [PMID: 25642984 PMCID: PMC4141265 DOI: 10.1186/1866-1955-6-31] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 04/23/2014] [Indexed: 02/07/2023] Open
Abstract
This paper summarizes key emerging issues in fragile X-associated tremor/ataxia syndrome (FXTAS) as presented at the First International Conference on the FMR1 Premutation: Basic Mechanisms & Clinical Involvement in 2013.
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Affiliation(s)
- Deborah A Hall
- Department of Neurological Sciences, Rush University, Chicago, IL, USA
| | - Rachael C Birch
- Department of Developmental Disability Neuropsychiatry, School of Psychiatry, University of New South Wales, Sydney, Australia
| | - Mathieu Anheim
- Département de Neurologie, Hôpitaux Universitaires de Strasbourg, Hôpital de Hautepierre, 67098 Strasbourg, Cedex, France ; Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM-U964/CNRS-UMR7104/Université de Strasbourg, 67404 Illkirch, France ; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
| | - Aia E Jønch
- Department of clinical Genetics, Kennedy Center, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Elizabeth Pintado
- Department of Medical Biochemistry and Molecular Biology, University of Seville, Sevilla, Spain
| | - Joanne O'Keefe
- Department of Anatomy & Cell Biology, Rush University, Chicago, IL, USA
| | - Julian N Trollor
- Department of Developmental Disability Neuropsychiatry, School of Psychiatry, University of New South Wales, Sydney, Australia ; Centre for Healthy Brain Ageing, University of New South Wales, Sydney, Australia
| | - Glenn T Stebbins
- Department of Neurological Sciences, Rush University, Chicago, IL, USA
| | - Randi J Hagerman
- Department of Pediatrics & M.I.N.D. Institute, University of California at Davis Medical Center, Sacramento, CA, USA
| | - Stanley Fahn
- Department of Neurology, Columbia University, New York, NY, USA
| | - Elizabeth Berry-Kravis
- Department of Neurological Sciences, Rush University, Chicago, IL, USA ; Departments of Pediatrics and Biochemistry, Rush University, Chicago, IL, USA
| | - Maureen A Leehey
- Department of Neurology, University of Colorado at Denver, Denver, CO, USA
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Abstract
This article summarizes the clinical findings, genetics, pathophysiology, and treatment of fragile X-associated tremor ataxia syndrome. The disorder occurs from a CGG repeat (55-200) expansion in the fragile X mental retardation 1 gene. It manifests clinically in kinetic tremor, gait ataxia, and executive dysfunction, usually in older men who carry the genetic abnormality. The disorder has distinct radiographic and pathologic findings. Symptomatic treatment is beneficial in some patients. The inheritance is X-linked and family members may be at risk for other fragile X-associated disorders. This information is useful to neurologists, general practitioners, and geneticists.
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Hall DA, O'keefe JA. Fragile x-associated tremor ataxia syndrome: the expanding clinical picture, pathophysiology, epidemiology, and update on treatment. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2012; 2. [PMID: 23439567 PMCID: PMC3570061 DOI: 10.7916/d8hd7tds] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 11/21/2011] [Indexed: 12/12/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive degenerative movement disorder characterized by kinetic tremor, cerebellar gait ataxia, parkinsonism, and cognitive decline. This disorder occurs in both males and females, frequently in families with children who have fragile X syndrome. The clinical features of this disorder, both classic and newly described, are summarized in this paper. In screening studies, fragile X mental retardation 1 (FMR1) gene premutation (55–200 CGG) expansions are most frequently seen in men with ataxia who have tested negative for spinocerebellar ataxias. Since the original description, the classic FXTAS phenotype has now been reported in females and in carriers of smaller (45–54 CGG) and larger (>200 CGG) expansions in FMR1. Premutation carriers may present with a Parkinson disease phenotype or hypotension, rather than with tremor and/or ataxia. Parkinsonism and gait ataxia may also be seen in individuals with gray zone (41–54 CGG) expansions. Studies regarding medication to treat the symptoms in FXTAS are few in number and suggest that medications targeted to specific symptoms, such as kinetic tremor or gait ataxia, may be most beneficial. Great progress has been made in regards to FXTAS research, likely given the readily available gene test and the screening of multiple family members, including parents and grandparents, of fragile X syndrome children. Expansion of genotypes and phenotypes in the disorder may suggest that a broader disease definition might be necessary in the future.
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Affiliation(s)
- Deborah A Hall
- Department of Neurological Sciences, Rush University, Chicago, Illinois, United States of America
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Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an under-recognized disorder that is a significant cause of late-adult-onset ataxia. The etiology is expansion of a trinucleotide repeat to the premutation range (55-200 CGG repeats) in the fragile X mental retardation 1 (FMR1) gene. Expansion to >200 CGGs causes fragile X syndrome, the most common heritable cause of cognitive impairment and autism. Core features of FXTAS include progressive action tremor and gait ataxia; with frequent, more variable features of cognitive decline, especially executive dysfunction, parkinsonism, neuropathy, and autonomic dysfunction. MR imaging shows generalized atrophy and frequently abnormal signal in the middle cerebellar peduncles. Autopsy reveals intranuclear inclusions in neurons and astrocytes and dystrophic white matter. FXTAS is likely due to an RNA toxic gain-of-function of the expanded-repeat mRNA. The disorder typically affects male premutation carriers over age 50, and, less often, females. Females also are at increased risk for primary ovarian insufficiency, chronic muscle pain, and thyroid disease. Treatment targets specific symptoms, but progression of disability is relentless. Although the contribution of FXTAS to the morbidity and mortality of the aging population requires further study, the disorder is likely the most common single-gene form of tremor and ataxia in the older adult population.
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Affiliation(s)
- Maureen A Leehey
- Department of Neurology, University of Colorado at Denver Health Sciences Center, Denver, CO, USA.
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Loesch D, Hagerman R. Unstable Mutations in the FMR1 Gene and the Phenotypes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 769:78-114. [DOI: 10.1007/978-1-4614-5434-2_6] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
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Leehey MA. Fragile X-associated tremor/ataxia syndrome: clinical phenotype, diagnosis, and treatment. J Investig Med 2011; 57:830-6. [PMID: 19574929 DOI: 10.2310/jim.0b013e3181af59c4] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a CGG repeat expansion in the premutation range (55-200) in the fragile X mental retardation 1 gene. Onset is typically in the early seventh decade, and men are principally affected. The major signs are cerebellar gait ataxia, intention tremor, frontal executive dysfunction, and global brain atrophy. Other frequent findings are parkinsonism (mild), peripheral neuropathy, psychiatric symptoms (depression, anxiety, and agitation), and autonomic dysfunction. The clinical presentation is heterogeneous, with individuals presenting with varied dominating signs, such as tremor, dementia, or neuropathy. Magnetic resonance imaging shows atrophy and patchy white matter lesions in the cerebral hemispheres and middle cerebellar peduncles. The latter has been designated the middle cerebellar peduncle sign, which occurs in about 60% of affected men, and is relatively specific for FXTAS. Affected females generally have less severe disease, less cognitive decline, and some symptoms different from that of men, for example, muscle pain. Management of FXTAS is complex and includes assessment of the patient's neurological and medical deficits, treatment of symptoms, and provision of relevant referrals, especially genetic counseling. Treatment is empirical, based on anecdotal experience and on knowledge of what works for symptoms of other disorders that also exist in FXTAS. Presently, the disorder is underrecognized because the first published report was only in 2001 and because the presentation is variable and mainly consists of a combination of signs common in the elderly. However, accurate diagnosis is critical for the patient and for the family because they need education regarding their genetic and health risks.
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Affiliation(s)
- Maureen A Leehey
- Department of Neurology, University of Colorado Denver, Aurora, CO 80045, USA.
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Luciano GL, Brennan MJ, Rothberg MB. Postprandial hypotension. Am J Med 2010; 123:281.e1-6. [PMID: 20193838 DOI: 10.1016/j.amjmed.2009.06.026] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 06/21/2009] [Accepted: 06/24/2009] [Indexed: 12/01/2022]
Abstract
Postprandial hypotension is both common in geriatric patients and an important but under-recognized cause of syncope. Other populations at risk include those with Parkinson disease and autonomic failure. The mechanism is not clearly understood, but appears to be secondary to a blunted sympathetic response to a meal. This review discusses the epidemiology, risk factors, and pathophysiology of postprandial hypotension in the elderly, as well as diagnosis and treatment strategies. Diagnosis can be made based on ambulatory blood pressure monitoring and patient symptoms. Lifestyle modifications such as increased water intake before eating or substituting 6 smaller meals daily for 3 larger meals may be effective treatment options. However, data from randomized, controlled trials are limited. Increased awareness of this disease may lead to improved quality of life, decreased falls and injuries, and the avoidance of unnecessary testing.
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Bourgeois J, Coffey S, Rivera SM, Hessl D, Gane LW, Tassone F, Greco C, Finucane B, Nelson L, Berry-Kravis E, Grigsby J, Hagerman PJ, Hagerman RJ. A review of fragile X premutation disorders: expanding the psychiatric perspective. J Clin Psychiatry 2009; 70:852-62. [PMID: 19422761 PMCID: PMC2705685 DOI: 10.4088/jcp.08m04476] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Accepted: 11/11/2008] [Indexed: 01/28/2023]
Abstract
CONTEXT Fragile X premutation conditions are associated with a significant degree of psychopathology and thus are of interest to the psychiatrist. Remarkable advances at the molecular level have enhanced our understanding of fragile X premutation disorders. OBJECTIVE The authors review the genetic, molecular, neuroimaging, and clinical (systemic, neurologic, and psychiatric) manifestations of the premutation carrier state (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene. DATA SOURCES The search for the psychiatric clinical manifestations of fragile X-associated conditions was accomplished by PubMed for clinical papers published between 1970 and 2008 with the following search terms: Fragile X syndrome, depression, psychosis, anxiety, and dementia. STUDY SELECTION Articles addressing psychiatric symptoms in premutation carriers based on review of the abstracts were reviewed. As the majority of the literature on this topic is based on case reports and small case series, these were included in the database. RESULTS Reported clinical manifestations of psychiatric illness in premutation carriers include an apparently significant rate of cognitive, mood, anxiety, and other psychiatric disorders. Fragile X premutation-associated conditions are part of the clinical differential diagnosis of several psychiatric syndromes, particularly in pedigrees with known fragile X syndrome cases. CONCLUSIONS Fragile X-associated psychiatric manifestations serve as a useful model for a molecular genesis of neuropsychiatric illness. Because of the multigenerational expression of fragile X-associated neuropsychiatric illness, there is a prominent role for genetic testing and genetic counseling of patients and their relatives. Genetic testing is confirmatory of the FMR1 premutation and is an essential component of the clinical evaluation. Psychopharmacologic and psychotherapeutic treatment of fragile X-associated psychiatric illnesses may improve patient function and assist in adaptation to the burden of a genetic neuropsychiatric illness.
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Affiliation(s)
- James Bourgeois
- Department of Psychiatry and Behavioral Sciences, University of California, Davis Medical Center, Sacramento, CA
| | - Sarah Coffey
- M.I.N.D. Institute, University of California, Davis Medical Center, Sacramento, CA., Department of Pediatrics, University of California, Davis Medical Center, Sacramento, CA
| | - Susan M. Rivera
- M.I.N.D. Institute, University of California, Davis Medical Center, Sacramento, CA., Department of Psychology, University of California, Davis
| | - David Hessl
- M.I.N.D. Institute, University of California, Davis Medical Center, Sacramento, CA., Department of Psychiatry and Behavioral Sciences, University of California, Davis, Sacramento, CA
| | - Louise W. Gane
- M.I.N.D. Institute, University of California, Davis Medical Center, Sacramento, CA
| | - Flora Tassone
- M.I.N.D. Institute, University of California, Davis Medical Center, Sacramento, CA., Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento, CA
| | - Claudia Greco
- Department of Pathology, University of California, Davis Medical Center, School of Medicine, Sacramento, CA
| | - Brenda Finucane
- Genetic Services, Elwyn, Inc., 111 Elwyn Road, Elwyn, Pennsylvania
| | - Lawrence Nelson
- Integrative Reproductive Medicine Unit, Intramural Research Program on Reproductive and Adult Endocrinology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Elizabeth Berry-Kravis
- Departments of Pediatrics, Neurological Sciences, and Biochemistry, RUSH University Medical Center, Chicago, IL
| | - Jim Grigsby
- Department of Medicine, University of Colorado at Denver and Health Sciences Center, Denver, CO
| | - Paul J. Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento, CA
| | - Randi J. Hagerman
- M.I.N.D. Institute, University of California, Davis Medical Center, Sacramento, CA., Department of Pediatrics, University of California, Davis Medical Center, Sacramento, CA
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Sallansonnet-Froment M, De Greslan T, Roux X, Bounolleau P, Ouologuem M, Taillia H, Ricard D, Renard JL. [Tremor/ataxia syndrome related to Fragile X premutation]. Presse Med 2009; 39:187-95. [PMID: 19419833 DOI: 10.1016/j.lpm.2008.12.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 12/20/2008] [Accepted: 12/31/2008] [Indexed: 11/20/2022] Open
Abstract
The FXTAS syndrome (Fragile X-associated tremor/ataxia syndrome) is a specific neurodegenerative syndrome affecting subjects carrying a premutation of the FMR1 (fragile X mental retardation 1) gene. It affects mainly men with the premutation and aged more than 50 years. This syndrome is separate and distinct from the fragile X syndrome. The FXTAS syndrome remains underestimated today. It should be considered in patients older than 50 years with tremors and cerebellar ataxia, especially when Parkinson disease or cognitive disorders are present or when there is a family history of infertility, early menopause, or mental retardation. In these patients, hyperintense signals of mid-cerebellar peduncle images on T2 and FLAIR MRI justify genetic testing for the FMR1 premutation.
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Affiliation(s)
- Magali Sallansonnet-Froment
- Hôpital d'instruction des armées du Val-de-Grâce, Service de neurologie, F-75230 Paris Cedex 05, B.P.1-00446 Armées, France.
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Berry-Kravis E, Abrams L, Coffey SM, Hall DA, Greco C, Gane LW, Grigsby J, Bourgeois JA, Finucane B, Jacquemont S, Brunberg JA, Zhang L, Lin J, Tassone F, Hagerman PJ, Hagerman RJ, Leehey MA. Fragile X-associated tremor/ataxia syndrome: clinical features, genetics, and testing guidelines. Mov Disord 2008; 22:2018-30, quiz 2140. [PMID: 17618523 DOI: 10.1002/mds.21493] [Citation(s) in RCA: 220] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder with core features of action tremor and cerebellar gait ataxia. Frequent associated findings include parkinsonism, executive function deficits and dementia, neuropathy, and dysautonomia. Magnetic Resonance Imaging studies in FXTAS demonstrate increased T2 signal intensity in the middle cerebellar peduncles (MCP sign) in the majority of patients. Similar signal alterations are seen in deep and subependymal cerebral white matter, as is general cortical and subcortical atrophy. The major neuropathological feature of FXTAS is the presence of intranuclear, neuronal, and astrocytic, inclusions in broad distribution throughout the brain and brainstem. FXTAS is caused by moderate expansions (55-200 repeats; premutation range) of a CGG trinucleotide in the fragile X mental retardation 1 (FMR1) gene, the same gene which causes fragile X syndrome when in the full mutation range (200 or greater CGG repeats). The pathogenic mechanism is related to overexpression and toxicity of the FMR1 mRNA per se. Although only recently discovered, and hence currently under-diagnosed, FXTAS is likely to be one of the most common single-gene disorders leading to neurodegeneration in males. In this report, we review information available on the clinical, radiological, and pathological features, and prevalence and management of FXTAS. We also provide guidelines for the practitioner to assist with identifying appropriate patients for DNA testing for FXTAS, as well as recommendations for genetic counseling once a diagnosis of FXTAS is made.
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Leehey MA, Berry-Kravis E, Goetz CG, Zhang L, Hall DA, Li L, Rice CD, Lara R, Cogswell J, Reynolds A, Gane L, Jacquemont S, Tassone F, Grigsby J, Hagerman RJ, Hagerman PJ. FMR1 CGG repeat length predicts motor dysfunction in premutation carriers. Neurology 2007; 70:1397-402. [PMID: 18057320 DOI: 10.1212/01.wnl.0000281692.98200.f5] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Fragile X-associated tremor/ataxia syndrome (FXTAS) is a recently described, underrecognized neurodegenerative disorder of aging fragile X mental retardation 1 (FMR1) premutation carriers, particularly men. Core motor features are action tremor, gait ataxia, and parkinsonism. Carriers have expanded CGG repeats (55 to 200); larger expansions cause fragile X syndrome, the most common heritable cause of mental retardation and autism. This study determines whether CGG repeat length correlates with severity and type of motor dysfunction in premutation carriers. METHODS Persons aged >or=50 years with a family history of fragile X syndrome underwent structured videotaping. Movement disorder neurologists, blinded to carrier status, scored the tapes using modified standardized rating scales. CGG repeat length analyses for women incorporated the activation ratio, which measures the percentage of normal active chromosome X alleles. RESULTS Male carriers (n = 54) had significantly worse total motor scores, especially in tremor and ataxia, than age-matched male noncarriers (n = 51). There was a trend toward a difference between women carriers (n = 82) and noncarriers (n = 39). In men, increasing CGG repeat correlated with greater impairment in all motor signs. In women, when activation ratio was considered, increasing CGG correlated with greater ataxia. CONCLUSIONS CGG repeat size is significantly associated with overall motor impairment in premutation carriers. Whereas this association is most pronounced for men and covers overall motor impairment-tremor, ataxia, and parkinsonism-the association exists for ataxia among women carriers. This is the first report of a significant correlation between the premutation status and a motor feature of fragile X-associated tremor/ataxia syndrome in women.
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Affiliation(s)
- M A Leehey
- Department of Neurology, University of Colorado at Denver and Health Sciences Center, Denver, CO 80262, USA.
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