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Depienne C, Mandel JL. 30 years of repeat expansion disorders: What have we learned and what are the remaining challenges? Am J Hum Genet 2021; 108:764-785. [PMID: 33811808 DOI: 10.1016/j.ajhg.2021.03.011] [Citation(s) in RCA: 147] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/05/2021] [Indexed: 12/13/2022] Open
Abstract
Tandem repeats represent one of the most abundant class of variations in human genomes, which are polymorphic by nature and become highly unstable in a length-dependent manner. The expansion of repeat length across generations is a well-established process that results in human disorders mainly affecting the central nervous system. At least 50 disorders associated with expansion loci have been described to date, with half recognized only in the last ten years, as prior methodological difficulties limited their identification. These limitations still apply to the current widely used molecular diagnostic methods (exome or gene panels) and thus result in missed diagnosis detrimental to affected individuals and their families, especially for disorders that are very rare and/or clinically not recognizable. Most of these disorders have been identified through family-driven approaches and many others likely remain to be identified. The recent development of long-read technologies provides a unique opportunity to systematically investigate the contribution of tandem repeats and repeat expansions to the genetic architecture of human disorders. In this review, we summarize the current and most recent knowledge about the genetics of repeat expansion disorders and the diversity of their pathophysiological mechanisms and outline the perspectives of developing personalized treatments in the future.
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Akinyemi RO, Owolabi MO, Oyeniyi T, Ovbiagele B, Arnett DK, Tiwari HK, Walker R, Ogunniyi A, Kalaria RN. Neurogenomics in Africa: Perspectives, progress, possibilities and priorities. J Neurol Sci 2016; 366:213-223. [PMID: 27288810 DOI: 10.1016/j.jns.2016.05.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 05/04/2016] [Indexed: 11/18/2022]
Abstract
The understanding of the genetic basis of neurological disorders has grown rapidly in the last two decades. Despite the genomic heterogeneity within African populations, large-scale candidate gene or linkage and exome studies are lacking. However, current knowledge on neurogenetics in African populations is limited and geographically very uneven. Isolated reports indicate the existence of autosomal dominant or recessive conditions incorporating cerebrovascular, movement, neuromuscular, seizure and motor neuron disorders in Africans. In addition, few African families with neurodegenerative disorders associated with dementia have been characterized in North, West and South Africa. The current insurgency in genomic research triggered by among others the Human Health and Heredity (H3) Africa Initiative indicates that there are unique opportunities to advance our knowledge and understanding of the influence of genomic variation on the pattern, presentations and prognosis of neurological disorders in Africa. These have enormous potential to unmask novel genes and molecular pathways germane to the neurobiology of brain disorders. It would facilitate the development of novel diagnostics, preventative and targeted treatments in the new paradigm of precision medicine. Nevertheless, it is crucial to strike a balance between effective traditional public health strategies and personalized genome based care. The translational barriers can be overcome through robust stakeholder engagement and sustainable multilevel, multigenerational and multidisciplinary capacity building and infrastructural development for genomic medicine in Africa.
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Affiliation(s)
- Rufus O Akinyemi
- Institute for Advanced Medical Research and Training, College of Medicine, University of Ibadan, Nigeria; Institute of Neuroscience, Newcastle University, UK.
| | - Mayowa O Owolabi
- Department of Medicine, College of Medicine, University of Ibadan, Nigeria
| | | | - Bruce Ovbiagele
- Department of Neurosciences, Medical University of South Carolina, USA
| | - Donna K Arnett
- School of Public Health, University of Alabama at Birmingham, USA
| | - Hemant K Tiwari
- School of Public Health, University of Alabama at Birmingham, USA
| | - Richard Walker
- Institute of Health and Society, Newcastle University, UK
| | - Adesola Ogunniyi
- Department of Medicine, College of Medicine, University of Ibadan, Nigeria
| | - Raj N Kalaria
- Institute of Neuroscience, Newcastle University, UK.
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Saadah M, El Beshari M, Saadah L, Hamdallah H, Alloub Z, Al Zaabi AA, Ben-Mussa A, Ben-Nour A. Progressive myoclonic epilepsy type 1: Report of an Emirati family and literature review. EPILEPSY & BEHAVIOR CASE REPORTS 2014; 2:112-7. [PMID: 25667885 PMCID: PMC4307868 DOI: 10.1016/j.ebcr.2014.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 03/25/2014] [Indexed: 11/24/2022]
Abstract
PURPOSE Progressive myoclonic epilepsy type one is a neurodegenerative disorder characterized by action- and stimulus-sensitive myoclonus, tonic-clonic seizures, progressive cerebellar ataxia, preserved cognition, and poor outcome. The authors report clinical, neurophysiological, radiological, and genetic findings of an Emirati family with five affected siblings and review the literature. METHODS All data concerning familial and clinical history, neurologic examination, laboratory tests, electroencephalogram, brain imaging, and DNA analysis were examined. RESULTS Genetic testing confirmed the diagnosis of autosomal recessive progressive myoclonic epilepsy type 1 (EPM1) in two males and three females. The median age at onset was three years. Action- or stimulus-sensitive myoclonus and generalized seizures were recorded in 100% of our patients, at median age at onset of 3 and 4 years, respectively. Multisegmental myoclonus and generalized status myoclonicus were observed in 80% of our patients. Dysarthria and ataxia developed in 100% of our patients. Vitamin D deficiency and recurrent viral infections were noticed in 100% of our cohort. Cognitive, learning, and motor dysfunctions were involved in 100% of our patients. The sphincters were affected in 60% of our patients. Abnormal EEG was recorded in 100% of our cohort. Generalized brain atrophy progressively occurred in 60% of our patients. Phenytoin and carbamazepine were used in 60% of our patients with worsening effect. Valproate and levetiracetam were used in 100% of our patients with improving effect. CONCLUSIONS This is the first to report a family with EPM1 in UAE. Our study emphasized a particular phenotype expressed as earlier disease onset, severe myoclonus, and generalized seizures. Cognitive, cerebellar, motor, and autonomic dysfunctions and brain atrophy were also earlier at onset and more severe than previously reported. Recurrent viral infections are another unique feature. This constellation in tout à fait was not previously reported in the literature.
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Affiliation(s)
- Mohammed Saadah
- Department of Neurology, Zayed Military Hospital, Abu Dhabi, United Arab Emirates
| | - Mahfoud El Beshari
- Department of Neurology, Zayed Military Hospital, Abu Dhabi, United Arab Emirates
| | - Loai Saadah
- Department of Pharmacy, Zayed Military Hospital, Abu Dhabi, United Arab Emirates
| | - Hisham Hamdallah
- Department of Neurology, Zayed Military Hospital, Abu Dhabi, United Arab Emirates
| | - Zeinab Alloub
- Department of Pediatrics, Zayed Military Hospital, Abu Dhabi, United Arab Emirates
| | - Amani Ali Al Zaabi
- Department of Neurology, Zayed Military Hospital, Abu Dhabi, United Arab Emirates
| | | | - Anwaar Ben-Nour
- Department of Neurology, 7th October Hospital, Benghazi, Libya
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Kecmanović M, Ristić AJ, Ercegovac M, Keckarević-Marković M, Keckarević D, Sokić D, Romac S. A Shared Haplotype Indicates a Founder Event in Unverricht–Lundborg Disease Patients from Serbia. Int J Neurosci 2013; 124:102-9. [DOI: 10.3109/00207454.2013.828723] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Brault V, Martin B, Costet N, Bizot JC, Hérault Y. Characterization of PTZ-induced seizure susceptibility in a down syndrome mouse model that overexpresses CSTB. PLoS One 2011; 6:e27845. [PMID: 22140471 PMCID: PMC3227573 DOI: 10.1371/journal.pone.0027845] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 10/26/2011] [Indexed: 12/27/2022] Open
Abstract
Down syndrome (DS) is a complex genetic syndrome characterized by intellectual disability, dysmorphism and variable additional physiological traits. Current research progress has begun to decipher the neural mechanisms underlying cognitive impairment, leading to new therapeutic perspectives. Pentylenetetrazol (PTZ) has recently been found to have positive effects on learning and memory capacities of a DS mouse model and is foreseen to treat DS patients. But PTZ is also known to be a convulsant drug at higher dose and DS persons are more prone to epileptic seizures than the general population. This raises concerns over what long-term effects of treatment might be in the DS population. The cause of increased propensity for epilepsy in the DS population and which Hsa21 gene(s) are implicated remain unknown. Among Hsa21 candidate genes in epilepsy, CSTB, coding for the cystein protease inhibitor cystatin B, is involved in progressive myoclonus epilepsy and ataxia in both mice and human. Thus we aim to evaluate the effect of an increase in Cstb gene dosage on spontaneous epileptic activity and susceptibility to PTZ-induced seizure. To this end we generated a new mouse model trisomic for Cstb by homologous recombination. We verified that increasing copy number of Cstb from Trisomy (Ts) to Tetrasomy (Tt) was driving overexpression of the gene in the brain, we checked transgenic animals for presence of locomotor activity and electroencephalogram (EEG) abnormalities characteristic of myoclonic epilepsy and we tested if those animals were prone to PTZ-induced seizure. Overall, the results of the analysis shows that an increase in Cstb does not induce any spontaneous epileptic activity and neither increase or decrease the propensity of Ts and Tt mice to myoclonic seizures suggesting that Ctsb dosage should not interfere with PTZ-treatment.
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Affiliation(s)
- Véronique Brault
- Department of Translational Medicine and Neurogenetics, Institut de Génétique Biologie Moléculaire et Cellulaire (IGBMC), Inserm U596, CNRS UMR7104, Université de Strasbourg, Illkirch, France
| | - Benoît Martin
- Inserm U642, Rennes, France
- Laboratoire Traitement du Signal et de l'Image, Université de Rennes 1, Rennes, France
| | - Nathalie Costet
- Inserm U642, Rennes, France
- Laboratoire Traitement du Signal et de l'Image, Université de Rennes 1, Rennes, France
| | | | - Yann Hérault
- Department of Translational Medicine and Neurogenetics, Institut de Génétique Biologie Moléculaire et Cellulaire (IGBMC), Inserm U596, CNRS UMR7104, Université de Strasbourg, Illkirch, France
- Transgenese et Archivage Animaux Modèles, TAAM, CNRS, UPS44, Orléans, France
- Institut Français Clinique de la Souris, GIE CERBM, Illkirch, France
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Khiari HM, Franceschetti S, Jovic N, Mrabet A, Genton P. Death in Unverricht–Lundborg disease. Neurol Sci 2009; 30:315-8. [DOI: 10.1007/s10072-009-0102-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 05/18/2009] [Indexed: 11/28/2022]
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Kecmanović M, Ristić AJ, Sokić D, Keckarević-Marković M, Vojvodić N, Ercegovac M, Janković S, Keckarević D, Savić-Pavićević D, Romac S. Coexistence of Unverricht-Lundborg disease and congenital deafness: Molecular resolution of a complex comorbidity. Epilepsia 2009; 50:1612-5. [DOI: 10.1111/j.1528-1167.2008.01937.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hamadouche T, Poitelon Y, Genin E, Chaouch M, Tazir M, Kassouri N, Nouioua S, Chaouch A, Boccaccio I, Benhassine T, De Sandre-Giovannoli A, Grid D, Lévy N, Delague V. Founder effect and estimation of the age of the c.892C>T (p.Arg298Cys) mutation in LMNA associated to Charcot-Marie-Tooth subtype CMT2B1 in families from North Western Africa. Ann Hum Genet 2008; 72:590-7. [PMID: 18549403 DOI: 10.1111/j.1469-1809.2008.00456.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
CMT2B1, an axonal subtype (MIM 605588) of the Charcot-Marie-Tooth disease, is an autosomal recessive motor and sensory neuropathy characterized by progressive muscular and sensory loss in the distal extremities with chronic distal weakness. The genetic defect associated with the disease is, to date, a unique homozygous missense mutation, p.Arg298Cys (c.892C>T), in the LMNA gene. So far, this mutation has only been found in affected individuals originating from a restricted region of North Western Africa (northwest of Algeria and east of Morocco), strongly suggesting a founder effect. In order to address this hypothesis, genotyping of both STRs and intragenic SNPs was performed at the LMNA locus, at chromosome 1q21.2-q21.3, in 42 individuals affected with CMT2B1 from 25 Algerian families. Our results indicate that the affected individuals share a common ancestral haplotype in a region of about 1.0 Mb (1 cM) and that the most recent common ancestor would have lived about 800-900 years ago (95% confidence interval: 550 to 1300 years).
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Affiliation(s)
- T Hamadouche
- INSERM UMR_S 910, Génétique Médicale et Génomique Fonctionnelle, Université de La Méditerranée, Faculté de Médecine Timone, Marseille, France
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Kälviäinen R, Khyuppenen J, Koskenkorva P, Eriksson K, Vanninen R, Mervaala E. Clinical picture of EPM1-Unverricht-Lundborg disease. Epilepsia 2008; 49:549-56. [PMID: 18325013 DOI: 10.1111/j.1528-1167.2008.01546.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Unverricht-Lundborg disease (ULD), progressive myoclonic epilepsy type 1 (EPM1, OMIM254800), is an autosomal recessively inherited neurodegenerative disorder characterized by age of onset from 6 to 16 years, stimulus-sensitive myoclonus, and tonic-clonic epileptic seizures. Some years after the onset ataxia, incoordination, intentional tremor, and dysarthria develop. Individuals with EPM1 are mentally alert but show emotional lability, depression, and mild decline in intellectual performance over time. The diagnosis of EPM1 can be confirmed by identifying disease-causing mutations in a cysteine protease inhibitor cystatin B (CSTB) gene. Symptomatic pharmacologic and rehabilitative management, including psychosocial support, are the mainstay of EPM1 patients' care. Valproic acid, the first drug of choice, diminishes myoclonus and the frequency of generalized seizures. Clonazepam and high-dose piracetam are used to treat myoclonus, whereas levetiracetam seems to be effective for both myoclonus and generalized seizures. There are a number of agents that aggravate clinical course of EPM1 such as phenytoin aggravating the associated neurologic symptoms or even accelerating cerebellar degeneration. Sodium channel blockers (carbamazepine, oxcarbazepine) and GABAergic drugs (tiagabine, vigabatrin) as well as gabapentin and pregabalin may aggravate myoclonus and myoclonic seizures. EPM1 patients need lifelong clinical follow-up, including evaluation of the drug-treatment and comprehensive rehabilitation.
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Affiliation(s)
- Reetta Kälviäinen
- Kuopio Epilepsy Center, Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
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Abstract
Unverricht-Lundborg disease (ULD) is the purest and least severe type of progressive myoclonus epilepsy (PME), and is not associated with progressive cognitive deficit. Symptoms stabilize in adulthood, with a varying degree of permanent, often severe handicap that is mostly due to myoclonus. The disorder follows an autosomal recessive transmission pattern, with onset between 8 and 15 years years of age of generalized tonic-clonic or clonic-tonic-clonic seizures, action myoclonus (massive or segmental), photosensitivity, and often ataxia. Prevalence varies, it is highest in certain isolates (Finland, La Réunion Island) and in region with higher levels of inbreeding (Maghreb). ULD is due to a deficit in cystatin B (stefin B), but the mechanisms leading to the clinical symptoms are not well understood. The causative gene, PME1, was identified in 1991 and localized to chromosome 21q22.3. The mutations are mainly expansions of the CCCCGCCCCGCG dodecamer, but less common point mutations were also found. A variant has been recently reported in a Palestinian family, with localization on chromosome 12. The diagnosis of ULD is made on the basis of family history, age at onset, geographical and ethnic context, and on the typical features of myoclonus and epilepsy, in the absence of cognitive and sensory deficits. Neurophysiological evaluation yields interesting, but unspecific results. There are no biological or pathological markers for ULD. Molecular analysis confirms the diagnosis in most patients. Genetic testing for heterozygotes and even prenatal diagnosis are possible, although seldom performed, if the mutation has been identified. In spite of intensive research, ULD has yet to reveal all of its secrets. It remains a quasi "idiopathic" type of PME, with limited progression. Clinicians and patients are still waiting for an etiologically oriented treatment, which should, ideally, be admnistered early in the course of the disease, if possible before the onset of invalidating symptoms.
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Affiliation(s)
- P Genton
- Centre Saint-Paul--H. Gastaut, Marseille.
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Magaudda A, Ferlazzo E, Nguyen VH, Genton P. Unverricht-Lundborg Disease, a Condition with Self-limited Progression: Long-term Follow-up of 20 Patients. Epilepsia 2006; 47:860-6. [PMID: 16686650 DOI: 10.1111/j.1528-1167.2006.00553.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To assess the long-term evolution of Unverricht-Lundborg disease (ULD), especially concerning myoclonus, seizures, and EEG characteristics. METHODS We retrospectively evaluated 20 patients (six women, 14 men; mean age, 37.9 years; range, 26-53 years) with ULD who had been closely followed up since the onset of the disease (mean age, 12.3 years; range, 6-17 years) for an average of 25.6 years (range, 13-41 years). ULD was confirmed by genetic tests in all. We used simplified myoclonus and seizure rating scales. RESULTS The geographic origin of the patients was Northern Africa in nine, France in two, Italy in six, and mixed European in three. Three patients were severely handicapped, six led fully autonomous lives, and 11 required various degrees of social support. Myoclonus progressed only during the first 5 years of disease. Major seizures occurred in 19. Three patients had a single seizure, and eight became seizure free, whereas six had rare seizures, and two had frequent attacks. Overall, seizures became much less frequent after 10 years of evolution. EEG changes abated during follow-up: background activity remained stable or improved, spontaneous discharges disappeared, and photoparoxysmal responses were abolished in all patients but two. CONCLUSIONS This study shows that ULD progresses only over a limited period and stabilizes thereafter. This self-limited progression may be the consequence of age-related apoptosis of selected neuronal populations.
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Affiliation(s)
- Adriana Magaudda
- Center for Diagnosis and Care of Epilepsy, Department of Neurosciences, Anesthesiological and Psychiatric Sciences, University of Messina, Italy.
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Horiuchi H, Osawa M, Furutani R, Morita M, Tian W, Awatsu Y, Shimazaki H, Umetsu K. Polymerase Chain Reaction-Based Analysis Using Deaminated DNA of Dodecamer Expansions in CSTB, Associated with Unverricht-Lundborg Myoclonus Epilepsy. ACTA ACUST UNITED AC 2005; 9:328-33. [PMID: 16379547 DOI: 10.1089/gte.2005.9.328] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Progressive myoclonus epilepsy of the Unverricht-Lundborg type is an autosomal recessive disorder that is characterized clinically by myoclonic seizures and ataxia. The majority of affected individuals carry repeat expansions of a dodecamer in the promoter region of the cystatin B gene. The unusually high GC content of this tract is refractory to conventional polymerase chain reaction (PCR), and, as a result, a circumventive procedure involving the deamination of DNA with sodium bisulfite has been proposed. This study evaluates the effectiveness of this deamination modification for the detection of dodecamer repeat variants. An analysis of 258 healthy Japanese individuals revealed an allele with four copies of the dodecamer repeat with a frequency of 0.01, in addition to the more commonly observed two and three copy repeat alleles. Homozygous repeat expansions 600 and 680 base pairs in length were detected in the analyses of two affected individuals. For these cases, sequencing, along with an alternative PCR-stutter formation, revealed 41 and 48 copies, respectively, of the dodecamer repeat. The complete conversion of C to T was observed in the expanded tracts, indicating that no methylation occurred at the CpG sites. Based on these results, it was concluded that the use of deaminated DNA allows for a precise analysis of consecutive GC tracts.
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Affiliation(s)
- H Horiuchi
- Department of Experimental and Forensic Pathology, Yamagata University Faculty of Medicine, Japan.
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Lalioti MD, Antonarakis SE, Scott HS. The epilepsy, the protease inhibitor and the dodecamer: progressive myoclonus epilepsy, cystatin b and a 12-mer repeat expansion. Cytogenet Genome Res 2004; 100:213-23. [PMID: 14526183 DOI: 10.1159/000072857] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2003] [Accepted: 03/01/2003] [Indexed: 11/19/2022] Open
Abstract
Progressive myoclonus epilepsy 1 (EPM1) or Unverricht-Lundborg disease is a human autosomal recessive neurodegenerative disorder caused by mutations in cystatin B (CSTB). The CSTB gene maps to human chromosome 21 and encodes an inhibitor of lysosomal cysteine proteases. Five point mutations have been found, two of which are seen in numerous unrelated patients. However, the main CSTB mutation in EPM1, even among patients of different ethnic origins, is an expansion of a dodecamer repeat (CCCCGCCCCGCG) in the 5' flanking area of CSTB. Most normal alleles contain either two or three repeats, while rarer normal alleles that are highly unstable contain between 12 and 17 repeats. Mutant expanded alleles have been reported to contain between 30 and 80 copies and are also highly unstable, particularly via parental transmission. There is no apparent correlation between mutant repeat length and disease phenotype. While the repeat expansion is outside the CSTB transcriptional unit, it results in a marked decrease in CSTB expression, at least in certain cell types in vitro. CSTB homozygous knockout mice show some parallels to the phenotype of human EPM1 including myoclonic seizures, development of ataxia and neuropathological changes associated with cell loss via apoptosis. Loss of CSTB function due to mutations is consistent with the observed neurodegenerative pathology and phenotype, but the functional link to the epileptic phenotype of EPM1 remains largely unknown.
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Affiliation(s)
- M D Lalioti
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
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Moulard B, Darcel F, Mignard D, Jeanpierre M, Genton P, Cartault F, Yaouanq J, Roubertie A, Biraben A, Buresi C, Malafosse A. Founder Effect in Patients with Unverricht-Lundborg Disease on Reunion Island. Epilepsia 2003; 44:1357-60. [PMID: 14510831 DOI: 10.1046/j.1528-1157.2003.03703.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE Unverricht-Lundborg disease (ULD) is the most frequent form of progressive myoclonus epilepsy. ULD is caused mostly by a homozygous expansion of a dodecamer repeat in the cystatin B gene (CSTB) promoter. We present here a clinical and molecular study of 14 ULD patients originating from Reunion Island, a French island in the Indian Ocean. METHODS These ULD patients were clinically evaluated, and the diagnosis of ULD was confirmed molecularly. We analyzed 12 microsatellites flanking CSTB and estimated the date of introduction of the ULD mutation on Reunion Island. RESULTS These cases were clinically very similar, with the typical myoclonus syndrome associated with generalized tonic-clonic seizures, cerebellar involvement and, in some cases, mild mental deterioration. The mean age at onset was 9.6 years (range, 5-14 years), and the mean disease duration was 27 years (range, 5-47 years). The 14 patients harbored the typical ULD mutation, with variable degrees of expansion (mean of 56.3 repeats; range, 49-63). A founder effect was detected, with all but one of the Reunion ULD chromosomes displaying expansions belonging to the same haplotype, 1-1-1-2-6-4-3. We estimated the date of arrival of the most recent common ancestor (MRCA) of these patients on Reunion Island to the middle of the eighteenth century. CONCLUSIONS These Reunion ULD patients displayed a homogeneous phenotype. Our molecular results are compatible with the instability of the repeat expansion and revealed a founder effect in Reunion ULD patients and the existence of a MRCA about 12 generations ago.
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Affiliation(s)
- Bruno Moulard
- Division de Neuropsychiatrie, Hôpitaux Universitaires de Genève, Switzerland.
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Norio R. The Finnish Disease Heritage III: the individual diseases. Hum Genet 2003; 112:470-526. [PMID: 12627297 DOI: 10.1007/s00439-002-0877-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2002] [Accepted: 10/30/2002] [Indexed: 02/03/2023]
Abstract
This article is the third and last in a series entitled The Finnish Disease Heritage I-III. All the 36 rare hereditary diseases belonging to this entity are described for clinical and molecular genetic purposes, based on the Finnish experience gathered over a period of half a century. In addition, five other diseases are mentioned. They may be included in the list of the "Finnish diseases" after adequate complementary studies.
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Affiliation(s)
- Reijo Norio
- Department of Medical Genetics, The Family Federation of Finland, Helsinki, Finland.
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