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Sánchez Marín JP, Sienes Bailo P, Lahoz Alonso R, Capablo Liesa JL, Gazulla Abio J, Giménez Muñoz JA, Modrego Pardo PJ, Pardiñas Barón B, Izquierdo Álvarez S. Myotonic dystrophy type 1: 13 years of experience at a tertiary hospital. Clinical and epidemiological study and genotype-phenotype correlation. Neurologia 2023; 38:530-540. [PMID: 37437658 DOI: 10.1016/j.nrleng.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 02/08/2021] [Indexed: 07/14/2023] Open
Abstract
INTRODUCTION The incidence of myotonic dystrophy type 1 (DM1), a disease with great phenotypic variety, in our region is unknown. This study aims to estimate the incidence of DM1 at our hospital (a reference centre in Aragon, Spain) and to identify the characteristics of our population (genotype-phenotype correlation). METHODS Retrospective, descriptive study of 459 patients classified according to the number of CTG repeats, as follows: normal (5-35), premutation (36-50), protomutation (51-80), small expansions (81-150), intermediate expansions (151-1000), and large expansions (> 1000). Furthermore, according to clinical phenotype, patients were categorised as unaffected (5-50 CTG repeats), mild form or asymptomatic (51-150), classical form (151-1000), and severe form (> 1000). RESULTS The incidence of DM1 was 20.61 cases per million person-years (95% CI, 19.59-21.63). An inverse correlation was observed between the number of CTG repeats and the age at genetic diagnosis (ρ = -0.547; 95% CI, -0.610 to -0.375; P < .001). CTG5 was the most frequent polymorphic allele in healthy individuals. Of all patients with DM1, 28.3% presented the mild or asymptomatic form, 59.1% the classical form, and 12.6% the severe form. Inheritance was maternal in 35.1% of cases, paternal in 59.4%, and uncertain in 5.5%. In mild forms, frontal balding in men was the most prevalent phenotypic trait, as well as myotonia and cataracts, while in the classical form, ptosis, facial weakness, voice and pronunciation alterations, myotonia, and fatigue/sleepiness were most frequent. CONCLUSIONS The incidence of DM1 in Aragon is significant. Multidisciplinary study of the phenotype of patients with DM1 is key to early diagnosis and personalised management.
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Affiliation(s)
- J P Sánchez Marín
- Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | - P Sienes Bailo
- Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, Spain.
| | - R Lahoz Alonso
- Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | - J L Capablo Liesa
- Servicio de Neurología, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | - J Gazulla Abio
- Servicio de Neurología, Hospital Universitario Miguel Servet, Zaragoza, Spain; Neurología, Centro Médico de Especialidades Ramón y Cajal, Zaragoza, Spain
| | | | - P J Modrego Pardo
- Servicio de Neurología, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | - B Pardiñas Barón
- Servicio de Neurología, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | - S Izquierdo Álvarez
- Sección de Genética Clínica, Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, Spain
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Anesthésie et maladies neuromusculaires : myopathies et myasthénie. ANESTHÉSIE & RÉANIMATION 2023. [DOI: 10.1016/j.anrea.2023.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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Sánchez Marín JP, Sienes Bailo P, Lahoz Alonso R, Capablo Liesa JL, Gazulla Abio J, Giménez Muñoz JA, Modrego Pardo PJ, Pardiñas Barón B, Izquierdo Álvarez S. Myotonic dystrophy type1: 13years of experience at a tertiary hospital. Clinical and epidemiological study and genotype-phenotype correlation. Neurologia 2021; 38:S0213-4853(21)00050-5. [PMID: 33972121 DOI: 10.1016/j.nrl.2021.02.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 02/04/2021] [Accepted: 02/08/2021] [Indexed: 02/07/2023] Open
Abstract
INTRODUCTION The incidence of myotonic dystrophy type1 (DM1), a disease with great phenotypic variety, in our region is unknown. This study aims to estimate the incidence of DM1 at our hospital (a reference centre in Aragon, Spain) and to identify the characteristics of our population (genotype-phenotype correlation). METHODS Retrospective, descriptive study of 459 patients classified according to the number of CTG repeats, as follows: normal (5-35), premutation (36-50), protomutation (51-80), small expansions (81-150), intermediate expansions (151-1000), and large expansions (>1000). Furthermore, according to clinical phenotype, patients were categorised as unaffected (5-50 CTG repeats), mild form or asymptomatic (51-150), classical form (151-1000), and severe form (>1000). RESULTS The incidence of DM1 was 20.61 cases per million person-years (95%CI: 19.59-21.63). An inverse correlation was observed between the number of CTG repeats and the age at genetic diagnosis (ρ=-0.547; 95%CI: -0.610 to -0.375; P<.001). CTG5 was the most frequent polymorphic allele in healthy individuals. Of all patients with DM1, 28.3% presented the mild or asymptomatic form, 59.1% the classical form, and 12.6% the severe form. Inheritance was maternal in 35.1% of cases, paternal in 59.4%, and uncertain in 5.5%. In mild forms, frontal balding in men was the most prevalent phenotypic trait, as well as myotonia and cataracts, while in the classical form, ptosis, facial weakness, voice and pronunciation alterations, myotonia, and fatigue/sleepiness were most frequent. CONCLUSIONS The incidence of DM1 in Aragon is significant. Multidisciplinary study of the phenotype of patients with DM1 is key to early diagnosis and personalised management.
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Affiliation(s)
- J P Sánchez Marín
- Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, España
| | - P Sienes Bailo
- Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, España.
| | - R Lahoz Alonso
- Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, España
| | - J L Capablo Liesa
- Servicio de Neurología, Hospital Universitario Miguel Servet, Zaragoza, España
| | - J Gazulla Abio
- Servicio de Neurología, Hospital Universitario Miguel Servet, Zaragoza, España; Neurología, Centro Médico de Especialidades Ramón y Cajal, Zaragoza, España
| | | | - P J Modrego Pardo
- Servicio de Neurología, Hospital Universitario Miguel Servet, Zaragoza, España
| | - B Pardiñas Barón
- Servicio de Neurología, Hospital Universitario Miguel Servet, Zaragoza, España
| | - S Izquierdo Álvarez
- Sección de Genética Clínica, Servicio de Bioquímica Clínica, Hospital Universitario Miguel Servet, Zaragoza, España
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Stokes M, Varughese N, Iannaccone S, Castro D. Clinical and genetic characteristics of childhood-onset myotonic dystrophy. Muscle Nerve 2019; 60:732-738. [PMID: 31520483 DOI: 10.1002/mus.26716] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 09/10/2019] [Accepted: 09/12/2019] [Indexed: 01/22/2023]
Abstract
INTRODUCTION Myotonic dystrophy type 1 (DM1) is caused by a CTG (cytosine-thymine-guanine) trinucleotide repeat expansion. Congenital DM (CDM) presents in the first month of life, whereas individuals with infantile and juvenile DM1 have later onset of symptoms. METHODS We performed a retrospective chart review of patients with childhood-onset DM1 seen at one of three locations in Dallas, Texas between 1990 and 2018. Symptoms, disease course, cognitive features, and family history were reviewed. RESULTS Seventy-four patients were included; CDM was diagnosed in 52 patients. There was maternal inheritance in 74% of patients. CTG repeat number ranged from 143 to 2300. Neuropsychiatric and cognitive deficits were common. Over half of the patients had GI disturbances, and orthopedic complications were common. DISCUSSION Myotonic dystrophy type 1 in children requires a multidisciplinary approach to management. Presenting symptoms vary, and repeat expansion size does not necessarily directly relate to severity of symptoms. A consensus for outcome measures is required.
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Affiliation(s)
- Mathew Stokes
- Department of Pediatrics & Neurology, Division of Pediatric Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas.,Children's Medical Center Dallas, Dallas, Texas
| | - Natasha Varughese
- Department of Pediatrics & Neurology, Division of Pediatric Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas.,Children's Medical Center Dallas, Dallas, Texas
| | - Susan Iannaccone
- Department of Pediatrics & Neurology, Division of Pediatric Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas.,Children's Medical Center Dallas, Dallas, Texas
| | - Diana Castro
- Department of Pediatrics & Neurology, Division of Pediatric Neurology, The University of Texas Southwestern Medical Center, Dallas, Texas.,Children's Medical Center Dallas, Dallas, Texas
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Gonçalves D, Fonseca R, Leal S, Campos A, Valente E. Anesthetic management of a patient with Steinert disease. J Clin Anesth 2019; 59:101-102. [PMID: 31310950 DOI: 10.1016/j.jclinane.2019.06.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/10/2019] [Accepted: 06/09/2019] [Indexed: 11/25/2022]
Affiliation(s)
- Décia Gonçalves
- Department of Anesthesiology, Centro Hospitalar de Leiria, EPE, Leiria, Portugal.
| | - Raquel Fonseca
- Department of Anesthesiology, Centro Hospitalar de Leiria, EPE, Leiria, Portugal
| | - Sandra Leal
- Department of Anesthesiology, Centro Hospitalar de Leiria, EPE, Leiria, Portugal
| | - Ana Campos
- Department of Anesthesiology, Centro Hospitalar de Leiria, EPE, Leiria, Portugal
| | - Elisabete Valente
- Department of Anesthesiology, Centro Hospitalar de Leiria, EPE, Leiria, Portugal
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Wenninger S, Montagnese F, Schoser B. Core Clinical Phenotypes in Myotonic Dystrophies. Front Neurol 2018; 9:303. [PMID: 29770119 PMCID: PMC5941986 DOI: 10.3389/fneur.2018.00303] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 04/18/2018] [Indexed: 12/22/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) and type 2 (DM2) represent the most frequent multisystemic muscular dystrophies in adulthood. They are progressive, autosomal dominant diseases caused by an abnormal expansion of an unstable nucleotide repeat located in the non-coding region of their respective genes DMPK for DM1 and CNBP in DM2. Clinically, these multisystemic disorders are characterized by a high variability of muscular and extramuscular symptoms, often causing a delay in diagnosis. For both subtypes, many symptoms overlap, but some differences allow their clinical distinction. This article highlights the clinical core features of myotonic dystrophies, thus facilitating their early recognition and diagnosis. Particular attention will be given to signs and symptoms of muscular involvement, to issues related to respiratory impairment, and to the multiorgan involvement. This article is part of a Special Issue entitled “Beyond Borders: Myotonic Dystrophies—A European Perception.”
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Affiliation(s)
- Stephan Wenninger
- Friedrich-Baur-Institute, Klinikum der Universität München, Munich, Germany
| | | | - Benedikt Schoser
- Friedrich-Baur-Institute, Klinikum der Universität München, Munich, Germany
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Rakočević-Stojanović V, Perić S, Pešović J, Senćanić I, Božić M, Šviković S, Brkušanin M, Savić-Pavićević D. Genetic testing of individuals with pre-senile cataract identifies patients with myotonic dystrophy type 2. Eur J Neurol 2017; 24:e79-e80. [PMID: 29024355 DOI: 10.1111/ene.13401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/25/2017] [Indexed: 11/30/2022]
Affiliation(s)
- V Rakočević-Stojanović
- Neurology Clinic, Clinical Center of Serbia, University of Belgrade School of Medicine, Belgrade, Serbia
| | - S Perić
- Neurology Clinic, Clinical Center of Serbia, University of Belgrade School of Medicine, Belgrade, Serbia
| | - J Pešović
- Center for Human Molecular Genetics, University of Belgrade Faculty of Biology, Belgrade, Serbia
| | - I Senćanić
- Ophthalmology Department, Clinical Centre Zvezdara, Belgrade, Serbia
| | - M Božić
- Ophthalmology Clinic, Clinical Centre of Serbia, Belgrade, Serbia
| | - S Šviković
- Center for Human Molecular Genetics, University of Belgrade Faculty of Biology, Belgrade, Serbia
| | - M Brkušanin
- Center for Human Molecular Genetics, University of Belgrade Faculty of Biology, Belgrade, Serbia
| | - D Savić-Pavićević
- Center for Human Molecular Genetics, University of Belgrade Faculty of Biology, Belgrade, Serbia
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Van Den Hende K, Durand S, Mesnage R, Filleron A, Cambonie G. [Congenital myotonic dystrophy type I in a very premature neonate: ethical concerns]. Arch Pediatr 2015; 22:1042-6. [PMID: 26321353 DOI: 10.1016/j.arcped.2015.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Revised: 06/22/2015] [Accepted: 07/06/2015] [Indexed: 10/23/2022]
Abstract
UNLABELLED The congenital form of myotonic dystrophy type I (CDM1) corresponds to a>1500 expansion of an unstable trinucleotide (CTG) repeat. Two prognostic factors predict the risk of death in early infancy: maturity of less than 35 weeks of gestation and neonatal invasive ventilation for more than 30 days. OBSERVATION The case of a 29-week-old premature female infant, conceived by in vitro fertilization, is reported. Generalized hypotonia led to the diagnosis of the disease. Ethical concertation about withdrawal or maintenance of intensive care was engaged, taking into account the prolonged ventilation, the degree of prematurity, and the parental wishes for maximum care. The infant was extubated after 2 months. At 17 months, motor development and precursors of language were delayed, and difficulties in feeding had required a gastrostomy. DISCUSSION Technical advances in neonatal intensive care now allow CDM1 children to survive prolonged ventilation. The signification of such ventilatory needs on patient outcome, particularly for motor handicaps, speech and language delay, and mental deficiency, remains uncertain. The potential impact of in vitro fertilization on disease expression may also be considered. CONCLUSION CDM1 is a severe condition, but variability in clinical manifestations and absence of genotype-phenotype correlation result in problems predicting prognosis at the individual level. Ethical issues about the level of care, notably for tracheostomy and gastrostomy, should be adapted to each case, in partnership with parents.
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Affiliation(s)
- K Van Den Hende
- Département de pédiatrie néonatale et réanimations, pôle hospitalo-universitaire Femme-Mère-Enfant, hôpital Arnaud-de-Villeneuve, centre hospitalier régional universitaire de Montpellier, 371, avenue du Doyen-Gaston-Giraud, 34295 Montpellier cedex 5, France
| | - S Durand
- Département de pédiatrie néonatale et réanimations, pôle hospitalo-universitaire Femme-Mère-Enfant, hôpital Arnaud-de-Villeneuve, centre hospitalier régional universitaire de Montpellier, 371, avenue du Doyen-Gaston-Giraud, 34295 Montpellier cedex 5, France.
| | - R Mesnage
- Département de pédiatrie néonatale et réanimations, pôle hospitalo-universitaire Femme-Mère-Enfant, hôpital Arnaud-de-Villeneuve, centre hospitalier régional universitaire de Montpellier, 371, avenue du Doyen-Gaston-Giraud, 34295 Montpellier cedex 5, France
| | - A Filleron
- Service de pédiatrie, hôpital Carémeau, centre hospitalier régional universitaire de Nîmes, place du Professeur-Debré, 30029 Nîmes cedex 9, France
| | - G Cambonie
- Département de pédiatrie néonatale et réanimations, pôle hospitalo-universitaire Femme-Mère-Enfant, hôpital Arnaud-de-Villeneuve, centre hospitalier régional universitaire de Montpellier, 371, avenue du Doyen-Gaston-Giraud, 34295 Montpellier cedex 5, France
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Roy AJ, Van den Bergh P, Van Damme P, Doggen K, Van Casteren V. Early stages of building a rare disease registry, methods and 2010 data from the Belgian Neuromuscular Disease Registry (BNMDR). Acta Neurol Belg 2015; 115:97-104. [PMID: 24957677 PMCID: PMC4438257 DOI: 10.1007/s13760-014-0320-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 05/30/2014] [Indexed: 12/11/2022]
Abstract
The Belgian Neuromuscular Disease Registry, commissioned in 2008, aims to collect data to improve knowledge on neuromuscular diseases and enhance quality health services for neuromuscular disease patients. This paper presents a clear outline of the strategy to launch a global national registry. All patients diagnosed with one of the predefined 62 neuromuscular disease groups and living in Belgium may be included in the yearly updated Registry. Basic core data is harvested through a newly designed web application by the six accredited neuromuscular reference centres. In 2010, 3,424 patients with a neuromuscular disorder were registered. The most prevalent disease group in the Registry is Hereditary Motor and Sensory Neuropathy, as similarly stated by other studies, albeit the prevalence in Belgium is five times lower: 6.5 per 100,000 in the north of Belgium, versus 17.0-41.0 per 100,000 in other areas of Europe. Very few patients were captured in the south of the country. With the aim to collect valuable epidemiological data, the registry targets to gather high quality data, that the sample to be representative of the population and that it be complete. The past 5 years of building the registry have improved its quality, albeit the consistent gap in data from the south of the country prevails, influencing the estimated prevalence of these diseases. To this day, the true burden of neuromuscular diseases in Belgium is not known but actions have been undertaken to address these issues.
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Affiliation(s)
- Anna J Roy
- Health Services Research Unit, Department of Public Health and Surveillance, Scientific Institute of Public Health, Health Services Research, 14 rue Juliette Wytsman, 1150, Brussels, Belgium,
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Win AK, Perattur PG, Pulido JS, Pulido CM, Lindor NM. Increased cancer risks in myotonic dystrophy. Mayo Clin Proc 2012; 87:130-5. [PMID: 22237010 PMCID: PMC3498332 DOI: 10.1016/j.mayocp.2011.09.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 09/14/2011] [Accepted: 09/26/2011] [Indexed: 12/30/2022]
Abstract
OBJECTIVE To estimate cancer risks for patients with myotonic dystrophy, given that increased risks for neoplasms in association with myotonic dystrophy type 1 and type 2 have been suggested in several studies but the risks of cancers have not been quantified. PATIENTS AND METHODS A cohort of 307 patients with myotonic dystrophy identified from medical records of Mayo Clinic in Rochester, MN, from January 1, l993, through May 28, 2010, was retrospectively analyzed. We estimated standardized incidence ratios (SIRs) of specific cancers for patients with myotonic dystrophy compared with age- and sex-specific cancer incidences of the general population. Age-dependent cumulative risks were calculated using the Kaplan-Meier method. RESULTS A total of 53 cancers were observed at a median age at diagnosis of 55 years. Patients with myotonic dystrophy had an increased risk of thyroid cancer (SIR, 5.54; 95% confidence interval [CI], 1.80-12.93; P=.001) and choroidal melanoma (SIR, 27.54; 95% CI, 3.34-99.49; P<.001). They may also have an increased risk of testicular cancer (SIR, 5.09; 95% CI, 0.62-18.38; P=.06) and prostate cancer (SIR, 2.21; 95% CI, 0.95-4.35; P=.05). The estimated cumulative risks at age 50 years were 1.72% (95% CI, 0.64%-4.55%) for thyroid cancer and 1.00% (95% CI, 0.25%-3.92%) for choroidal melanoma. There was no statistical evidence of an increased risk of brain, breast, colorectal, lung, renal, bladder, endometrial, or ovarian cancer; lymphoma; leukemia; or multiple myeloma. CONCLUSION Patients with myotonic dystrophy may have an increased risk of thyroid cancer and choroidal melanoma and, possibly, testicular and prostate cancers.
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Affiliation(s)
- Aung Ko Win
- Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, The University of Melbourne, Parkville, Victoria, Australia
| | | | | | | | - Noralane M. Lindor
- Department of Medical Genetics, Mayo Clinic, Rochester, MN
- Correspondence: Address to Noralane M. Lindor, MD, Department of Medical Genetics, Mayo Clinic, 200 First St SW, Rochester, MN 55905
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Population frequency of myotonic dystrophy: higher than expected frequency of myotonic dystrophy type 2 (DM2) mutation in Finland. Eur J Hum Genet 2011; 19:776-82. [PMID: 21364698 DOI: 10.1038/ejhg.2011.23] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Myotonic dystrophy (DM) is the most common adult-onset muscular dystrophy with an estimated prevalence of 1/8000. There are two genetically distinct types, DM1 and DM2. DM2 is generally milder with more phenotypic variability than the classic DM1. Our previous data on co-segregation of heterozygous recessive CLCN1 mutations in DM2 patients indicated a higher than expected DM2 prevalence. The aim of this study was to determine the DM2 and DM1 frequency in the general population, and to explore whether the DM2 mutation functions as a modifier in other neuromuscular diseases (NMD) to account for unexplained phenotypic variability. We genotyped 5535 Finnish individuals: 4532 normal blood donors, 606 patients with various non-myotonic NMD, 221 tibial muscular dystrophy patients and their 176 healthy relatives for the DM2 and DM1 mutations. We also genotyped an Italian idiopathic non-myotonic proximal myopathy cohort (n = 93) for the DM2 mutation. In 5496 samples analyzed for DM2, we found three DM2 mutations and two premutations. In 5511 samples analyzed for DM1, we found two DM1 mutations and two premutations. In the Italian cohort, we identified one patient with a DM2 mutation. We conclude that the DM2 mutation frequency is significantly higher in the general population (1/1830; P-value = 0.0326) than previously estimated. The identification of DM2 mutations in NMD patients with clinical phenotypes not previously associated with DM2 is of particular interest and is in accord with the high overall prevalence. On the basis of our results, DM2 appears more frequent than DM1, with most DM2 patients currently undiagnosed with symptoms frequently occurring in the elderly population.
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Distribution of CTG repeats at the DMPK gene in myotonic dystrophy patients and healthy individuals from the Mexican population. Mol Biol Rep 2010; 38:1341-6. [PMID: 20635151 DOI: 10.1007/s11033-010-0235-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 06/11/2010] [Indexed: 10/19/2022]
Abstract
Myotonic dystrophy type 1 (DM1), the most common form of adult muscular dystrophy, is caused by anormal expansion of CTG trinucleotide repeats located in the 3'-untranslated region of the DMPK gene. The clinical features of DM1 are multisystemic and highly variable, and the unstable nature of CTG expansion causes wide genotypic and phenotypic presentations. In this study, we described to our knowledge for the first time the molecular diagnosis of myotonic dystrophy type 1 patients in the Mexican population, applying a fluorescent PCR method in combination with capillary electrophoresis analysis of the amplified products. We identified expanded alleles in 45 out of 50 patients (90%) with clinical features of myotonic disease. Furthermore, genotyping of 400 healthy subjects revealed the presence of 25 different alleles, ranging in size from 5 to 34 repeats. The most frequent allele was 13 CTG repeats (38.87%) and the frequency for alleles over 18 CTG repeats was 6.7%. Molecular test is essential for DM1 diagnosis and distribution of the CTG repeat alleles present in the Mexican population are significantly different from those of other populations.
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