Acessibilidade / Reportar erro

The relative frequency of common neuromuscular diagnoses in a reference center

Frequência relativa de diagnósticos neuromusculares comuns em um serviço de referência

ABSTRACT

The diagnostic procedure in neuromuscular patients is complex. Knowledge of the relative frequency of neuromuscular diseases within the investigated population is important to allow the neurologist to perform the most appropriate diagnostic tests.

Objective:

To report the relative frequency of common neuromuscular diagnoses in a reference center.

Methods:

A 17-year chart review of patients with suspicion of myopathy.

Results:

Among 3,412 examinations, 1,603 (46.98%) yielded confirmatory results: 782 (48.78%) underwent molecular studies, and 821 (51.21%) had muscle biopsies. The most frequent diagnoses were: dystrophinopathy 460 (28.70%), mitochondriopathy 330 (20.59%), spinal muscular atrophy 158 (9.86%), limb girdle muscular dystrophy 157 (9.79%), Steinert myotonic dystrophy 138 (8.61%), facioscapulohumeral muscular dystrophy 99 (6.17%), and other diagnoses 261 (16.28%).

Conclusion:

Using the presently-available diagnostic techniques in this service, a specific limb girdle muscular dystrophy subtype diagnosis was reached in 61% of the patients. A neuromuscular-appropriate diagnosis is important for genetic counseling, rehabilitation orientation, and early treatment of respiratory and cardiac complications.

Keywords:
diagnosis; neuromuscular diseases; biopsy; epidemiology

RESUMO

O procedimento diagnóstico neuromuscular é complexo. O conhecimento da frequência relativa das doenças neuromusculares em uma população é importante para utilização dos testes diagnósticos mais apropriados.

Objetivo:

Relatar a frequência relativa de doenças neuromusculares em um centro de referência.

Métodos:

Revisão de prontuários de pacientes com suspeita de miopatia em 17 anos.

Resultados:

Dentre 3412 exames, 1603 (46,98%) foram confirmatórios: 782 (48,78%) estudos moleculares e 821 (51,21%) biópsias musculares. Os diagnósticos mais frequentes foram: distrofinopatia 460 (28,70%), mitocondriopatia 330 (20.59%), atrofia muscular espinhal 158 (9,86%), distrofia muscular cintura-membros 157 (9,79%), distrofia miotônica de Steinert 138 (8,61%), distrofia muscular face-escápulo-umeral 99 (6,17%) e outros diagnósticos 261 (16,28%).

Conclusão:

Utilizando as técnicas diagnósticas atualmente disponíveis em nosso serviço, o diagnóstico específico do subtipo de distrofia muscular cintura-membros foi obtido em 61% dos pacientes. O diagnóstico neuromuscular apropriado é importante para o aconselhamento genético, orientações de reabilitação e tratamento precoce de complicações respiratórias e cardíacas.

Palavras-chave:
diagnóstico; doenças neuromusculares; biópsia; epidemiologia

The diagnostic investigation of neuromuscular patients is a complex procedure that involves the participation of several professionals. Due to the high diversity of nosologic entities, it is necessary to use different kinds of examinations to confirm the clinical diagnostic hypotheses. It is useful to know the relative frequencies of neuromuscular disorders in the investigated population in order to utilize the most appropriate diagnostic tests. Some neuromuscular reference centers have previously reported on several Brazilian series on the diagnosis of myopathies and these are included on the discussion below11. Werneck LC, Lorenzoni PJ, Kay CS, Scola RH. Muscle biopsy in Pompe disease. Arq Neuropsiquiatr. 2013;71(5):284-9. https://doi.org/10.1590/0004-282X20130022
https://doi.org/10.1590/0004-282X2013002...
,22. Freund AA, Scola RH, Arndt RC, Lorenzoni PJ, Kay CK, Werneck LC. Duchenne and Becker muscular dystrophy: a molecular and immunohistochemical approach. Arq Neuropsiquiatr. 2007;65(1):73-6. https://doi.org/10.1590/S0004-282X2007000100016
https://doi.org/10.1590/S0004-282X200700...
,33. Comerlato EA, Scola RH, Werneck LC. Limb-girdle muscular dystrophy: an immunohistochemical diagnostic approach. Arq Neuropsiquiatr. 2005;63(2A):235-45. https://doi.org/10.1590/S0004-282X2005000200009
https://doi.org/10.1590/S0004-282X200500...
,44. Kiyomoto BH, Tengan CH, Costa CK, Oliveira AS, Schmidt B, Gabbai AA. Frequency of dystrophic muscle abnormalities in chronic progressive external ophthalmoplegia: analysis of 86 patients. J Neurol Neurosurg Psychiatry. 2006;77(4):541-3. https://doi.org/10.1136/jnnp.2005.079954
https://doi.org/10.1136/jnnp.2005.079954...
,55. Zatz M, de Paula F, Starling A, Vainzof M. The 10 autosomal recessive limb-girdle muscular dystrophies. Neuromuscul Disord. 2003;13(7-8):532-44. https://doi.org/10.1016/S0960-8966(03)00100-7
https://doi.org/10.1016/S0960-8966(03)00...
.

The aim of this study was to describe the relative frequency of neuromuscular diseases in a neuromuscular reference center.

METHODS

This was a retrospective, descriptive study of consecutive molecular examinations and muscle biopsies. Molecular examinations performed between April 19, 1999 and January 18, 2016, and muscle biopsies performed from October 3, 2000 to January 18, 2016 were included.

This study was approved by the Ethics and Research Committee.

Over 17 years, 3,412 patients, admitted to the neuromuscular outpatient clinic, were investigated for diseases in 16 diagnostic categories: 1,200 muscle biopsies and 2,212 molecular exams were performed.

The diagnostic procedure included the correlation between clinical data and laboratory tests, neurophysiology, and image results, with confirmation through molecular examinations, muscle biopsy, and specific enzymatic studies (e.g. alpha-glucosidase) in the patients or their relatives with a confirmed diagnosis. Inclusion criteria were molecular or muscle biopsy diagnoses in 16 categories: 1) Steinert myotonic dystrophy; 2) dystrophinopathy (Duchenne muscular dystrophy, Becker muscular dystrophy, intermediate phenotype dystrophinopathy, and female dystrophinopathy carriers); 3) facioscapulohumeral muscular dystrophy; 4) limb girdle muscular dystrophy, 5) spinal muscular atrophy; 6) congenital muscular dystrophy (except collagen VI disorders); 7) collagen VI neuromuscular disorders (Bethlem myopathy and Ullrich congenital muscular dystrophy); 8) congenital myopathies (subtypes: central core congenital myopathy, nemaline congenital myopathy, centronuclear/myotubular congenital myopathy, cap disease congenital myopathy, and congenital fiber type disproportion); 9) congenital myasthenic syndromes; 10) myofibrillar myopathy; 11) glycogen-storage disease type V (McArdle disease); 12) glycogen-storage disease type II (Pompe disease); 13) dermatomyositis; 14) sporadic inclusion body myositis; 15) other inflammatory myopathies (polymyositis, nonspecific myositis, and necrotizing immune myopathy); and 16) mitochondriopathy.

Exclusion criteria were: 1) myopathic abnormalities without other specifications; 2) neurogenic muscular abnormalities; 3) rare genetic syndromes and other neuromuscular disorders not included in the 16 investigated categories; and 4) duplicated examinations of patients submitted to both muscle biopsy and confirmatory molecular examinations (for duplicated examinations, the results were reported only once on the molecular examination tables) (Table 1).

Table 1
Diagnostic categories: inclusion and exclusion criteria.

Molecular examinations for dystrophinopathies included the investigation of dystrophin gene deletion through polymerase chain reaction (PCR), and deletion and duplication of the dystrophin gene through multiplex ligation-dependent probe amplification.

Molecular investigation of spinal muscular atrophy consisted of the detection of exons 7 and 8 deletion of the survival motor neuron (SMN) gene through PCR.

Facioscapulohumeral muscular dystrophy investigation consisted of the search of deletions of repeated tandem 3.3kb units within the D4Z4 locus at the 4q35 region through restriction fragments EcoRI/ HindIII, EcoRI/ AvrII and ApoI through Southern blotting with pulsed field electrophoresis (CHEF-DRIII - Biorad) followed by p13E-11 probe hybridization.

Steinert myotonic dystrophy molecular investigation was performed through the study of the dystrophia myotonica protein kinase (DMPK) gene CTG expansion with analysis of EcoRI and BamHI through Southern blotting, followed by pM10M-6 probe hybridization.

Calpainopathy (limb girdle muscular dystrophy type 2A [LGMD2A]) molecular investigation was performed with the search for 24 exons calpain gene point mutations (NM_000070.2) through denaturing high performance liquid chromatography and altered amplicon direct sequencing with the ABI 3130XL Genetic Analyzer (Applied Biosystems Sequencing (v. 5.2) software), and SeqScape (v. 2.5) analysis software, as well as a search for mutation on the Leiden database (www.dmd.nl/index.html).

Sarcoglycanopathy (LGMD2C, LGMD2D, LGMD2E, and LGMD2F) molecular investigation was performed with the study of alpha, beta, gamma, and delta sarcoglycan genes (respectively SGCD, SGCE, SGCC, and SGCF genes) through denaturing high performance liquid chromatography followed by altered amplicon direct sequencing with the ABI 3130XL Genetic Analyzer (Applied Biosystems Sequencing (v. 5.2) software), and SeqScape (v. 2.5) analysis software. The exons analyzed were alpha-sarcoglycan exon 3, beta-sarcoglycan exons 3 and 4, delta-sarcoglycan exon 8, and gamma-sarcoglycan exon 6, these being the most frequent mutations in Brazil66. Gouveia TL, Paim JF, Pavanello RC, Zatz M, Vainzof M. Sarcoglycanopathies: a multiplex molecular analysis for the most common mutations. Diagn Mol Pathol. 2006;15(2)95-100. https://doi.org/10.1097/00019606-200606000-00006
https://doi.org/10.1097/00019606-2006060...
.

Fukutin-related proteinopathy (LGMD2I) molecular investigation was performed with the fukutin-related protein (FKRP) investigation through denaturing high performance liquid chromatography followed by altered amplicon direct sequencing with the ABI 3130XL Genetic Analyzer (Applied Biosystems Sequencing (v. 5.2) software), and SeqScape (v. 2.5) analysis software.

The review of muscle biopsy diagnoses was performed through a Systematized Nomenclature of Medicine search in the fields “results” and “observations”. The standard procedure for muscle biopsy consisted of histochemical studies and, whenever necessary, immunohistochemical and electron microscopy studies. Histochemical investigations were performed on liquid nitrogen-frozen sections with: hematoxylin and eosin, Gomori modified trichrome, periodic acid-Schiff with and without diastase, Oil-red-O, myosin ATPase (pH9.4, pH4.6, and pH4.3), succinate dehydrogenase, cytochrome-c-oxidase, nicotinamide adenine dinucleotide, acid phosphatase, and nonspecific esterase. For patients under investigation for metabolic myopathy, tests for myophosphorylase, phosphofructokinase, and myoadenylate deaminase deficiencies were performed.

Diagnosis of a mitochondrial disorder included definite, probable and possible diagnostic criteria, codified by the Systematized Nomenclature of Medicine, considering histochemical, ultrastructural, molecular (from December 11, 2008), and respiratory chain enzymatic studies (from August 6, 2013).

A dysferlinopathy (LGMD2B) diagnosis was suspected for patients with a characteristic clinical presentation and phenotypic confirmation through immunohistochemistry for dysferlin deficiency.

A congenital myopathy diagnosis followed the International Standard of Care Committee for Congenital Myopathies77. North KN, Wang CH, Clarke N, Jungbluth H, Vainzof M, Dowling JJ et al. Approach to the diagnosis of congenital myopathies. Neuromuscul Disord. 2014;24(2):97-1 16. https://doi.org/10.1016/j.nmd.2013.11.003
https://doi.org/10.1016/j.nmd.2013.11.00...
criteria. Congenital myopathy subtypes included: “central core” congenital myopathy, nemaline congenital myopathy, centronuclear/myotubular congenital myopathy, congenital fiber type disproportion, and cap disease congenital myopathy. A congenital muscular dystrophy diagnosis followed the International Standard of Care Committee for Congenital Muscular Dystrophies criteria88. Bonnemann CG, Wang CH, Quijano-Roy S, Deconinck N, Bertini E, Ferreiro A et al. Diagnostic approach to the congenital muscular dystrophies. Neuromuscul Disord. 2014;24(4):289-311. https://doi.org/10.1016/j.nmd.2013.12.011
https://doi.org/10.1016/j.nmd.2013.12.01...
.

The congenital myasthenic syndrome diagnosis was made by considering anamnesis, clinical examination, and neurophysiological studies with significant repetitive nerve stimulation decrement with or without abnormal ultrastructural neuromuscular junctions99. Engel AG. Current status of the congenital myasthenic syndromes. Neuromuscul Disord. 2012;22(2):99-1 1 1. https://doi.org/10.1016/j.nmd.2011.10.009
https://doi.org/10.1016/j.nmd.2011.10.00...
.

RESULTS

The 2,212 molecular examinations corresponded to diagnostic categories 1 to 5. Category 1: 297 patients with clinical suspicion of Steinert myotonic dystrophy; category 2: 583 patients with clinical suspicion of dystrophinopathy; category 3: 352 patients with clinical suspicion of facioscapulohumeral muscular dystrophy; category 4: 299 patients with clinical suspicion of limb girdle muscular dystrophy, among them 139 patients with clinical suspicion of calpainopathy (LGMD2A), 58 with clinical suspicion of sarcoglycanopathy (LGMD2C/ LGMD2D/ LGMD2E/ LGMD2F), and 102 with clinical suspicion of fukutin-related proteinopathy (LGMD2I); and category 5: 681 patients with clinical suspicion of spinal muscular atrophy.

Of the 1,200 patients submitted to muscle biopsies, 1,199 had consecutive diagnoses with surgical procedures performed between October 3, 2000 and January 18, 2016, and one muscle biopsy had a review of the diagnosis during the study period, based on the muscle biopsy slides on material that had been previously collected on September 21, 1997 (one patient with a diagnosis of Pompe disease).

After the application of inclusion and exclusion criteria (Table 1) to the group of 3,412 patients, 1,603 (47%) patients were selected with confirmed diagnoses in the 16 diagnostic categories, 782 (48.8%) molecular examinations, and 821 (51.2%) muscle biopsies (Figure 1). The most frequent diagnoses were, in descending order: dystrophinopathy 460 (28.70%); definite, probable or possible mitochondriopathy 330 (20.59%); spinal muscular atrophy 158 (9.86%); limb girdle muscular dystrophy 157 (9.79%); Steinert myotonic dystrophy 138 (8.61%); facioscapulohumeral muscular dystrophy 99 (6.17%); congenital muscular dystrophy 79 (4.93%); congenital myopathy 58 (3.62%); polymyositis 35 (2.18%); dermatomyositis 34 (2.12%); sporadic inclusion body myositis 15 (0.94%); type VI collagenopathy 13 (0,81%); myofibrillar myopathy 11 (0.68%); congenital myasthenic syndrome 7 (0.44%); glycogen-storage disease type V/McArdle disease 5 (0.31%), and glycogen-storage disease type II/Pompe disease 4 (0.25%) (Figure 2) (Table 2).

Figure 1
Muscle biopsy-molecular neuromuscular examination ratio.
Figure 2
Relative frequencies of neuromuscular diagnoses.
Table 2
Relative frequency of neuromuscular disorders in a reference center.

There were 157 patients with limb girdle muscular dystrophy diagnoses. Among them, 34 were excluded from the muscle biopsy diagnosis table because they were submitted to further confirmatory molecular examinations. Therefore, 14 of the 24 patients with calpainopathy (LGMD2A) were excluded from the muscle biopsy table. Of the 26 patients with a sarcoglycanopathy diagnosis, 17 had the diagnosis made through muscle biopsy with immunohistochemistry and nine through molecular examinations; six were excluded from the muscle biopsy table as they had been submitted to both muscle biopsy and molecular examinations. Among the eight patients with a diagnosis of fukutinrelated proteinopathy, three were excluded from the muscle biopsy table as they were submitted to molecular examinations after the muscle biopsy. Three patients from the same family received the diagnosis of laminopathy (LGMD1B); three patients from another family received the diagnosis of caveolinopathy (LGMD1C) with the index case submitted to muscle biopsy, and three patients received the diagnosis of telethoninopathy (LGMD2G), confirmed through muscle biopsy with immunohistochemical deficiency on telethonin expression. With the presently-available techniques in our service, a confirmatory diagnosis of limb girdle muscular dystrophy subtype was made in 61% of the patients (Table 3)55. Zatz M, de Paula F, Starling A, Vainzof M. The 10 autosomal recessive limb-girdle muscular dystrophies. Neuromuscul Disord. 2003;13(7-8):532-44. https://doi.org/10.1016/S0960-8966(03)00100-7
https://doi.org/10.1016/S0960-8966(03)00...
,1010. Fanin M, Nascimbeni AC, Aurino S, Tasca E, Pegoraro E, Nigro V et al. Frequency of LGMD gene mutations in Italian patients with distinct clinical phenotypes. Neurology. 2009;72(16):1432-5. https://doi.org/10.1212/WNL.0b013e3181a1885e
https://doi.org/10.1212/WNL.0b013e3181a1...
,1111. Guglieri M, Magri F, D’Angelo MG, Prelle A, Morandi L, Rodolico C et al. Clinical, molecular, and protein correlations in a large sample of genetically diagnosed Italian limb girdle muscular dystrophy patients. Hum Mutat. 2008;29(2):258-66. https://doi.org/10.1002/humu.20642
https://doi.org/10.1002/humu.20642...
,1212. Gómez-Díaz B, Rosas-Vargas H, Roque-Ramírez B, Meza-Espinoza P Ruano-Calderón LA, Fernández-Valverde F et al. Immunodetection analysis of muscular dystrophies in Mexico. Muscle Nerve 2012;45(3):338-345. https://doi.org/10.1002/mus.22314
https://doi.org/10.1002/mus.22314...
,1313. Lo HP, Cooper ST, Evesson FJ, Seto JT, Chiotis M, Tay V et al. Limb-girdle muscular dystrophy: diagnostic evaluation, frequency and clues to pathogenesis. Neuromuscul Disord. 2008;18(1):34-44. https://doi.org/10.1016/j.nmd.2007.08.009
https://doi.org/10.1016/j.nmd.2007.08.00...
,1414. Norwood FL, Harling C, Chinnery PF, Eagle M, Bushby K, Straub V. Prevalence of genetic muscle disease in Northern England: in-depth analysis of a muscle clinic population. Brain. 2009;132(1 1):3175-86. https://doi.org/10.1093/brain/awp236
https://doi.org/10.1093/brain/awp236...
.

Table 3
Relative frequency of limb girdle muscular dystrophies.

There were 344 male patients with a diagnosis of dystrophinopathy. Among the 287 patients with a diagnosis of Duchenne muscular dystrophy, 184 were confirmed by molecular examination and 103 by muscle biopsy. Among 45 patients with Becker muscular dystrophy, 33 were confirmed by molecular examination and 12 by muscle biopsy. Among the 12 patients with intermediate dystrophinopathy phenotype, 10 were confirmed by molecular examination and two by muscle biopsy; four patients were excluded from the muscle biopsy table as they were later submitted to confirmatory molecular examination.

The initial date of the examinations varied according to the specific technique implementation: Steinert myotonic dystrophy molecular examinations started on April 19, 1999, dystrophinopathy on June 4, 2001, spinal muscular atrophy on May 29, 2000, facioscapulohumeral muscular dystrophy on February 12, 2003, calpainopathy (LGMD2A) on May 24, 2011, sarcoglycanopathy (LGMD2C, LGMD2D, LGMD2E, and LGMD2F) on May 26, 2011, fukutin-related proteinopathy on May 18, 2011. Muscle biopsies started in 1997 and the informatized diagnostic system, codified through the Systematized Nomenclature of Medicine, started on October 3, 2000.

After April 5, 2013, the diagnosis of dysferlinopathy was made through muscle biopsy with immunohistochemical deficiency in dysferlin expression after the confirmation of normal caveolin immunohistochemical expression and absent calpain mutation1515. Nguyen K, Bassez G, Krahn M, Bernard R, Laforêt P, Labelle V et al. Phenotypic study in 40 patients with dysferlin gene mutations: high frequency of atypical phenotypes. Arch Neurol. 2007;64(8):1 176-82. https://doi.org/10.1001/archneur.64.8.1176
https://doi.org/10.1001/archneur.64.8.11...
,1616. Groen EJ, Charlton R, Barresi R, Anderson LV, Eagle M, Hudson J et al. Analysis of the UK diagnostic strategy for limb girdle muscular dystrophy 2A. Brain. 2007;130(12):3237-49. https://doi.org/10.1093/brain/awm259
https://doi.org/10.1093/brain/awm259...
,1717. Muller JS, Piko H, Schoser BG, Schlotter-Weigel B, Reilich P, Gurster S et al. Novel splice site mutation in the caveolin-3 gene leading to autosomal recessive limb girdle muscular dystrophy. Neuromuscul Disord. 2006;1 6(7):432-6. https://doi.org/10.1016/j.nmd.2006.04.006
https://doi.org/10.1016/j.nmd.2006.04.00...
.

DISCUSSION

This study provided an estimated relative frequency of specific diagnoses (16 diagnostic categories) through molecular and muscle biopsy examinations in a neuromuscular reference clinic, over the last 17 years. About half the patients received a diagnosis, within one of the 16 categories, by molecular studies, and half by muscle biopsy. The relative frequency of neuromuscular diseases showed some similarities to the neuromuscular disease prevalence in a study in northern England1414. Norwood FL, Harling C, Chinnery PF, Eagle M, Bushby K, Straub V. Prevalence of genetic muscle disease in Northern England: in-depth analysis of a muscle clinic population. Brain. 2009;132(1 1):3175-86. https://doi.org/10.1093/brain/awp236
https://doi.org/10.1093/brain/awp236...
. In that study, the most frequent diagnoses, in descending order, were: myotonic dystrophy, mitochondriopathy, dystrophinopathy, facioscapulohumeral muscular dystrophy, limb girdle muscular dystrophy, spinal muscular atrophy, congenital muscular dystrophy, Bethlem type VI collagenopathy, and congenital myopathies (central core and nemaline)1414. Norwood FL, Harling C, Chinnery PF, Eagle M, Bushby K, Straub V. Prevalence of genetic muscle disease in Northern England: in-depth analysis of a muscle clinic population. Brain. 2009;132(1 1):3175-86. https://doi.org/10.1093/brain/awp236
https://doi.org/10.1093/brain/awp236...
. On the other hand, in the present study, the most frequent diagnoses, in descending order were: dystrophinopathy, mitochondriopathy, spinal muscular atrophy, limb girdle muscular dystrophy, Steinert myotonic dystrophy, and facioscapulohumeral muscular dystrophy. Due to methodological differences between both studies, it is not possible to conclude that the different relative frequencies of myotonic dystrophy in both studies should be attributed to differences in prevalences. Besides, only patients with myotonic dystrophy type 1 (Steinert myotonic dystrophy) were included in the present study, and type 2 myotonic dystrophy patients were not included in our study.

One limitation of this study is related to the diagnosis of dysferlinopathy, as the diagnosis was immunophenotypical and not genotypical. Considering the possibility of immunohistochemical secondary deficiencies, after April 5, 2013, the diagnosis was made taking into consideration the absence of calpain gene mutations, detection of calpain expression on Western blot, and detection of immunophenotypical caveolin expression1515. Nguyen K, Bassez G, Krahn M, Bernard R, Laforêt P, Labelle V et al. Phenotypic study in 40 patients with dysferlin gene mutations: high frequency of atypical phenotypes. Arch Neurol. 2007;64(8):1 176-82. https://doi.org/10.1001/archneur.64.8.1176
https://doi.org/10.1001/archneur.64.8.11...
,1616. Groen EJ, Charlton R, Barresi R, Anderson LV, Eagle M, Hudson J et al. Analysis of the UK diagnostic strategy for limb girdle muscular dystrophy 2A. Brain. 2007;130(12):3237-49. https://doi.org/10.1093/brain/awm259
https://doi.org/10.1093/brain/awm259...
,1717. Muller JS, Piko H, Schoser BG, Schlotter-Weigel B, Reilich P, Gurster S et al. Novel splice site mutation in the caveolin-3 gene leading to autosomal recessive limb girdle muscular dystrophy. Neuromuscul Disord. 2006;1 6(7):432-6. https://doi.org/10.1016/j.nmd.2006.04.006
https://doi.org/10.1016/j.nmd.2006.04.00...
(Table 3)55. Zatz M, de Paula F, Starling A, Vainzof M. The 10 autosomal recessive limb-girdle muscular dystrophies. Neuromuscul Disord. 2003;13(7-8):532-44. https://doi.org/10.1016/S0960-8966(03)00100-7
https://doi.org/10.1016/S0960-8966(03)00...
,1010. Fanin M, Nascimbeni AC, Aurino S, Tasca E, Pegoraro E, Nigro V et al. Frequency of LGMD gene mutations in Italian patients with distinct clinical phenotypes. Neurology. 2009;72(16):1432-5. https://doi.org/10.1212/WNL.0b013e3181a1885e
https://doi.org/10.1212/WNL.0b013e3181a1...
,1111. Guglieri M, Magri F, D’Angelo MG, Prelle A, Morandi L, Rodolico C et al. Clinical, molecular, and protein correlations in a large sample of genetically diagnosed Italian limb girdle muscular dystrophy patients. Hum Mutat. 2008;29(2):258-66. https://doi.org/10.1002/humu.20642
https://doi.org/10.1002/humu.20642...
,1212. Gómez-Díaz B, Rosas-Vargas H, Roque-Ramírez B, Meza-Espinoza P Ruano-Calderón LA, Fernández-Valverde F et al. Immunodetection analysis of muscular dystrophies in Mexico. Muscle Nerve 2012;45(3):338-345. https://doi.org/10.1002/mus.22314
https://doi.org/10.1002/mus.22314...
,1313. Lo HP, Cooper ST, Evesson FJ, Seto JT, Chiotis M, Tay V et al. Limb-girdle muscular dystrophy: diagnostic evaluation, frequency and clues to pathogenesis. Neuromuscul Disord. 2008;18(1):34-44. https://doi.org/10.1016/j.nmd.2007.08.009
https://doi.org/10.1016/j.nmd.2007.08.00...
,1414. Norwood FL, Harling C, Chinnery PF, Eagle M, Bushby K, Straub V. Prevalence of genetic muscle disease in Northern England: in-depth analysis of a muscle clinic population. Brain. 2009;132(1 1):3175-86. https://doi.org/10.1093/brain/awp236
https://doi.org/10.1093/brain/awp236...
.

Considering the diagnostic techniques available over the last 17 years, a conclusive, definite limb girdle muscular dystrophy subtype diagnosis was achieved in about 61% of the patients. In the previously-mentioned study in northern England, using muscle biopsy, immunohistochemistry, Western blot, and genetic sequencing, a conclusive limb girdle muscular dystrophy subtype diagnosis was achieved in 75% of the patients1818. Bushby K. Diagnosis and management of the limb girdle muscular dystrophies. Pract Neurol. 2009;9(6):314-23. https://doi.org/10.1136/jnnp.2009.193938
https://doi.org/10.1136/jnnp.2009.193938...
, whereas in another study in Italy, the percentage of confirmed limb girdle muscular dystrophy subtype diagnoses was 60%1010. Fanin M, Nascimbeni AC, Aurino S, Tasca E, Pegoraro E, Nigro V et al. Frequency of LGMD gene mutations in Italian patients with distinct clinical phenotypes. Neurology. 2009;72(16):1432-5. https://doi.org/10.1212/WNL.0b013e3181a1885e
https://doi.org/10.1212/WNL.0b013e3181a1...
,1818. Bushby K. Diagnosis and management of the limb girdle muscular dystrophies. Pract Neurol. 2009;9(6):314-23. https://doi.org/10.1136/jnnp.2009.193938
https://doi.org/10.1136/jnnp.2009.193938...
.

Even after the utilization of molecular examinations during the diagnostic procedure at the neuromuscular outpatient clinic, muscle biopsies represented 51.2% (821/1,603) of the examinations used to confirm the diagnosis. In a French study, muscle biopsies resulted in 43.6% of conclusive diagnoses1919. Cuisset JM, Maurage CA, Carpentier A, Briand G, Thévenon A, Rouaix N et al. [Muscle biopsy in children: usefulness in 2012]. Rev Neurol (Paris). 2013;169(8-9):632-9. French. https://doi.org/10.1016Zj.neurol.2012.11.011
https://doi.org/10.1016Zj.neurol.2012.11...
. In that study, the most frequent muscle biopsy diagnoses, in descending order were: congenital myopathy (for the most part corresponding to nonstructural congenital myopathy), progressive muscular dystrophy (for the most part corresponding to dystrophinopathy), mitochondrial, other metabolic myopathies, congenital muscular dystrophy, and dermatomyositis1919. Cuisset JM, Maurage CA, Carpentier A, Briand G, Thévenon A, Rouaix N et al. [Muscle biopsy in children: usefulness in 2012]. Rev Neurol (Paris). 2013;169(8-9):632-9. French. https://doi.org/10.1016Zj.neurol.2012.11.011
https://doi.org/10.1016Zj.neurol.2012.11...
. In the present study, the most frequent muscle biopsy diagnoses were, in descending order: mitochondriopathy, dystrophinopathy, limb girdle muscular dystrophy, inflammatory myopathy (polymyositis, dermatomyositis, and others), congenital muscular dystrophy, and congenital myopathy. The difference in the frequency of congenital myopathy between these studies may be due to the inclusion criteria as, in the present study, only five structural congenital myopathy subtypes were included (central core congenital myopathy, nemaline congenital myopathy, centronuclear/myotubular congenital myopathy, congenital fiber type disproportion, and cap disease congenital myopathy).

An analysis of 4,500 muscle biopsies performed from 1979 to 2012 in another Brazilian reference center identified 19 patients with Pompe disease11. Werneck LC, Lorenzoni PJ, Kay CS, Scola RH. Muscle biopsy in Pompe disease. Arq Neuropsiquiatr. 2013;71(5):284-9. https://doi.org/10.1590/0004-282X20130022
https://doi.org/10.1590/0004-282X2013002...
; the same reference center reported 106 patients submitted to dystrophin gene DNA analysis between 1999 and 2005 and at least one deletion was detected in 76 cases22. Freund AA, Scola RH, Arndt RC, Lorenzoni PJ, Kay CK, Werneck LC. Duchenne and Becker muscular dystrophy: a molecular and immunohistochemical approach. Arq Neuropsiquiatr. 2007;65(1):73-6. https://doi.org/10.1590/S0004-282X2007000100016
https://doi.org/10.1590/S0004-282X200700...
, as well as 56 patients with limb girdle muscular dystrophy submitted to muscle biopsy from 1976 to 200133. Comerlato EA, Scola RH, Werneck LC. Limb-girdle muscular dystrophy: an immunohistochemical diagnostic approach. Arq Neuropsiquiatr. 2005;63(2A):235-45. https://doi.org/10.1590/S0004-282X2005000200009
https://doi.org/10.1590/S0004-282X200500...
. From a group of 3,802 patients submitted to muscle biopsy between 1989 and 2001, at another Brazilian neuromuscular reference center, 86 patients were found to have mitochondriopathy of the chronic progressive external ophthalmoplegia subtype44. Kiyomoto BH, Tengan CH, Costa CK, Oliveira AS, Schmidt B, Gabbai AA. Frequency of dystrophic muscle abnormalities in chronic progressive external ophthalmoplegia: analysis of 86 patients. J Neurol Neurosurg Psychiatry. 2006;77(4):541-3. https://doi.org/10.1136/jnnp.2005.079954
https://doi.org/10.1136/jnnp.2005.079954...
. Yet another Brazilian group reported 120 unrelated families with limb girdle muscular dystrophy, submitted to molecular investigation until 200355. Zatz M, de Paula F, Starling A, Vainzof M. The 10 autosomal recessive limb-girdle muscular dystrophies. Neuromuscul Disord. 2003;13(7-8):532-44. https://doi.org/10.1016/S0960-8966(03)00100-7
https://doi.org/10.1016/S0960-8966(03)00...
.

With the advent of novel technologies, such as next generation sequencing, there is hope that the resolution rate of molecular studies may increase with consequent reduction in the number of undetermined diagnoses. This would provide the patients with: 1) adequate genetic counseling; 2) early clinical, respiratory and cardiac management; 3) rehabilitation orientation concerning gait prognosis and daily activities, according to the subtype of neuromuscular disorder.

Acknowledgments

We thank Cleides Campos de Oliveira and Simone Ferreira do Nascimento for muscle biopsy technical assistance.

References

  • 1
    Werneck LC, Lorenzoni PJ, Kay CS, Scola RH. Muscle biopsy in Pompe disease. Arq Neuropsiquiatr. 2013;71(5):284-9. https://doi.org/10.1590/0004-282X20130022
    » https://doi.org/10.1590/0004-282X20130022
  • 2
    Freund AA, Scola RH, Arndt RC, Lorenzoni PJ, Kay CK, Werneck LC. Duchenne and Becker muscular dystrophy: a molecular and immunohistochemical approach. Arq Neuropsiquiatr. 2007;65(1):73-6. https://doi.org/10.1590/S0004-282X2007000100016
    » https://doi.org/10.1590/S0004-282X2007000100016
  • 3
    Comerlato EA, Scola RH, Werneck LC. Limb-girdle muscular dystrophy: an immunohistochemical diagnostic approach. Arq Neuropsiquiatr. 2005;63(2A):235-45. https://doi.org/10.1590/S0004-282X2005000200009
    » https://doi.org/10.1590/S0004-282X2005000200009
  • 4
    Kiyomoto BH, Tengan CH, Costa CK, Oliveira AS, Schmidt B, Gabbai AA. Frequency of dystrophic muscle abnormalities in chronic progressive external ophthalmoplegia: analysis of 86 patients. J Neurol Neurosurg Psychiatry. 2006;77(4):541-3. https://doi.org/10.1136/jnnp.2005.079954
    » https://doi.org/10.1136/jnnp.2005.079954
  • 5
    Zatz M, de Paula F, Starling A, Vainzof M. The 10 autosomal recessive limb-girdle muscular dystrophies. Neuromuscul Disord. 2003;13(7-8):532-44. https://doi.org/10.1016/S0960-8966(03)00100-7
    » https://doi.org/10.1016/S0960-8966(03)00100-7
  • 6
    Gouveia TL, Paim JF, Pavanello RC, Zatz M, Vainzof M. Sarcoglycanopathies: a multiplex molecular analysis for the most common mutations. Diagn Mol Pathol. 2006;15(2)95-100. https://doi.org/10.1097/00019606-200606000-00006
    » https://doi.org/10.1097/00019606-200606000-00006
  • 7
    North KN, Wang CH, Clarke N, Jungbluth H, Vainzof M, Dowling JJ et al. Approach to the diagnosis of congenital myopathies. Neuromuscul Disord. 2014;24(2):97-1 16. https://doi.org/10.1016/j.nmd.2013.11.003
    » https://doi.org/10.1016/j.nmd.2013.11.003
  • 8
    Bonnemann CG, Wang CH, Quijano-Roy S, Deconinck N, Bertini E, Ferreiro A et al. Diagnostic approach to the congenital muscular dystrophies. Neuromuscul Disord. 2014;24(4):289-311. https://doi.org/10.1016/j.nmd.2013.12.011
    » https://doi.org/10.1016/j.nmd.2013.12.011
  • 9
    Engel AG. Current status of the congenital myasthenic syndromes. Neuromuscul Disord. 2012;22(2):99-1 1 1. https://doi.org/10.1016/j.nmd.2011.10.009
    » https://doi.org/10.1016/j.nmd.2011.10.009
  • 10
    Fanin M, Nascimbeni AC, Aurino S, Tasca E, Pegoraro E, Nigro V et al. Frequency of LGMD gene mutations in Italian patients with distinct clinical phenotypes. Neurology. 2009;72(16):1432-5. https://doi.org/10.1212/WNL.0b013e3181a1885e
    » https://doi.org/10.1212/WNL.0b013e3181a1885e
  • 11
    Guglieri M, Magri F, D’Angelo MG, Prelle A, Morandi L, Rodolico C et al. Clinical, molecular, and protein correlations in a large sample of genetically diagnosed Italian limb girdle muscular dystrophy patients. Hum Mutat. 2008;29(2):258-66. https://doi.org/10.1002/humu.20642
    » https://doi.org/10.1002/humu.20642
  • 12
    Gómez-Díaz B, Rosas-Vargas H, Roque-Ramírez B, Meza-Espinoza P Ruano-Calderón LA, Fernández-Valverde F et al. Immunodetection analysis of muscular dystrophies in Mexico. Muscle Nerve 2012;45(3):338-345. https://doi.org/10.1002/mus.22314
    » https://doi.org/10.1002/mus.22314
  • 13
    Lo HP, Cooper ST, Evesson FJ, Seto JT, Chiotis M, Tay V et al. Limb-girdle muscular dystrophy: diagnostic evaluation, frequency and clues to pathogenesis. Neuromuscul Disord. 2008;18(1):34-44. https://doi.org/10.1016/j.nmd.2007.08.009
    » https://doi.org/10.1016/j.nmd.2007.08.009
  • 14
    Norwood FL, Harling C, Chinnery PF, Eagle M, Bushby K, Straub V. Prevalence of genetic muscle disease in Northern England: in-depth analysis of a muscle clinic population. Brain. 2009;132(1 1):3175-86. https://doi.org/10.1093/brain/awp236
    » https://doi.org/10.1093/brain/awp236
  • 15
    Nguyen K, Bassez G, Krahn M, Bernard R, Laforêt P, Labelle V et al. Phenotypic study in 40 patients with dysferlin gene mutations: high frequency of atypical phenotypes. Arch Neurol. 2007;64(8):1 176-82. https://doi.org/10.1001/archneur.64.8.1176
    » https://doi.org/10.1001/archneur.64.8.1176
  • 16
    Groen EJ, Charlton R, Barresi R, Anderson LV, Eagle M, Hudson J et al. Analysis of the UK diagnostic strategy for limb girdle muscular dystrophy 2A. Brain. 2007;130(12):3237-49. https://doi.org/10.1093/brain/awm259
    » https://doi.org/10.1093/brain/awm259
  • 17
    Muller JS, Piko H, Schoser BG, Schlotter-Weigel B, Reilich P, Gurster S et al. Novel splice site mutation in the caveolin-3 gene leading to autosomal recessive limb girdle muscular dystrophy. Neuromuscul Disord. 2006;1 6(7):432-6. https://doi.org/10.1016/j.nmd.2006.04.006
    » https://doi.org/10.1016/j.nmd.2006.04.006
  • 18
    Bushby K. Diagnosis and management of the limb girdle muscular dystrophies. Pract Neurol. 2009;9(6):314-23. https://doi.org/10.1136/jnnp.2009.193938
    » https://doi.org/10.1136/jnnp.2009.193938
  • 19
    Cuisset JM, Maurage CA, Carpentier A, Briand G, Thévenon A, Rouaix N et al. [Muscle biopsy in children: usefulness in 2012]. Rev Neurol (Paris). 2013;169(8-9):632-9. French. https://doi.org/10.1016Zj.neurol.2012.11.011
    » https://doi.org/10.1016Zj.neurol.2012.11.011

Publication Dates

  • Publication in this collection
    Nov 2017

History

  • Received
    08 Aug 2016
  • Reviewed
    05 Dec 2016
  • Accepted
    11 Aug 2017
Academia Brasileira de Neurologia - ABNEURO R. Vergueiro, 1353 sl.1404 - Ed. Top Towers Offices Torre Norte, 04101-000 São Paulo SP Brazil, Tel.: +55 11 5084-9463 | +55 11 5083-3876 - São Paulo - SP - Brazil
E-mail: revista.arquivos@abneuro.org