Neuromuscular disorders are a group of rare heterogenous diseases with profound impact on quality of life, for which overall pediatric prevalence has rarely been reported. The purpose of this study was to determine the point prevalence of pediatric neuromuscular disorders and its subcategories in the central region of Portugal. Retrospective case identification was carried out in children with neuromuscular disorders seen between 1998 and 2020 from multiple data sources. Demographics, clinical and molecular diagnoses were registered. On January 1, 2020, the point overall prevalence in the population <18 years of age was 41.20/100 000 (95% confidence interval 34.51-49.19) for all neuromuscular disorders. The main case proportion were genetic disorders (95.7%). We found a relatively higher occurrence of limb-girdle muscular dystrophies, congenital myopathies, and spinal muscular atrophy and a slightly lower occurrence of Duchenne muscular dystrophy, hereditary spastic paraparesis, and acquired neuropathies compared to previous studies in other countries. Molecular confirmation was available in 69.5% of pediatric neuromuscular patients in our cohort.
Total prevalence is high in comparison with the data reported in the only previous study on the prevalence of pediatric neuromuscular disorders in our country. Our high definitive diagnostic rate underscores the importance of advances in investigative genetic techniques, particularly new sequencing technologies, in the diagnostic workup of neuromuscular patients.
DubowitzV. Muscle Disorders in Childhood. 2nd ed. W.B. Saunders Company Ltd; 1995.
2.
DeenenJCWHorlingsCGCVerschuurenJJGMVerbeekALMvan EngelenBGM. The epidemiology of neuromuscular disorders: a comprehensive overview of the literature. J Neuromuscul Dis. 2015;2(1):73‐85.
3.
BhattJM. The epidemiology of neuromuscular diseases. Neurol Clin. 2016 Nov;34(4):999‐1021.
4.
CareyIMBanchoffENirmalananthanN, et al.Prevalence and incidence of neuromuscular conditions in the UK between 2000 and 2019: a retrospective study using primary care data. PLoS One. 2021;16(12):e0261983.
5.
MüllerKIVan GhelueMLundIJonsrudCArntzenKA. The prevalence of hereditary neuromuscular disorders in northern Norway. Brain Behav. 2021;11(1):e01948.
6.
RoseLMcKimDLeasaD, et al.Trends in incidence, prevalence, and mortality of neuromuscular disease in Ontario, Canada: a population-based retrospective cohort study (2003-2014). PLoS One. 2019;14(3):e0210574.
7.
DeenenJCWvan DoornPAFaberCG, et al.The epidemiology of neuromuscular disorders: age at onset and gender in the Netherlands. Neuromuscul Disord. 2016;26(7):447‐452.
8.
LefterSHardimanORyanAM. A population-based epidemiologic study of adult neuromuscular disease in the Republic of Ireland. Neurology. 2017;88(3):304‐313.
9.
EmeryAE. Population frequencies of inherited neuromuscular diseases—a world survey. Neuromuscul Disord. 1991;1(1):19‐29.
10.
TangsrudSEHalvorsenS. Child neuromuscular disease in southern Norway: Prevalence, age and distribution of diagnosis with special reference to “non-Duchenne muscular dystrophy.”Clin Genet. 1988;34(3):145‐152.
11.
MerliniLStagniSBMarriEGranataC. Epidemiology of neuromuscular disorders in the under-20 population in Bologna Province, Italy. Neuromuscul Disord. 1992;2(3):197‐200.
12.
DarinNTuliniusM. Neuromuscular disorders in childhood: a descriptive epidemiological study from western Sweden. Neuromuscul Disord. 2000;10(1):1‐9.
13.
RasmussenMRisbergKVølloASkjeldalOH. Neuromuscular disorders in children in South-Eastern Norway. J Pediatr Neurol. 2012;10:95‐100.
14.
ChungBWongVIpP. Prevalence of neuromuscular diseases in Chinese children: a study in southern China. J Child Neurol. 2003;18(3):217‐219.
15.
WoodcockIRFraserLNormanPPysdenKManningSChildsA-M. The prevalence of neuromuscular disease in the paediatric population in Yorkshire, UK; variation by ethnicity and deprivation status. Dev Med Child Neurol. 2016;58(8):877‐883.
16.
MichelCCollinsC. Pediatric neuromuscular disorders. Pediatr Clin North Am. 2020;67(1):45‐57.
17.
SantosMAFinezaIMorenoT, et al.Epidemiology of neuromuscular disorders in Portugal at pediatric age. Neuromuscul Disord. 2006;16:644‐726.
18.
MahJKKorngutLDykemanJDayLPringsheimTJetteN. A systematic review and meta-analysis on the epidemiology of Duchenne and Becker muscular dystrophy. Neuromuscul Disord. 2014;24(6):482‐491.
19.
StraubVMurphyAUddB. 229th ENMC international workshop: limb girdle muscular dystrophies - Nomenclature and reformed classification Naarden, the Netherlands, 17-19 March 2017. Neuromuscul Disord. 2018;28:702‐710. England.
20.
JeppesenJGreenASteffensenBFRahbekJ. The Duchenne muscular dystrophy population in Denmark, 1977-2001: prevalence, incidence and survival in relation to the introduction of ventilator use. Neuromuscul Disord. 2003;13(10):804‐812.
21.
LiuWPajusaluSLakeNJ, et al.Estimating prevalence for limb-girdle muscular dystrophy based on public sequencing databases. Genet Med Off J Am Coll Med Genet. 2019;21(11):2512‐2520.
22.
McNallyEMPassos-BuenoMRBönnemannCG, et al.Mild and severe muscular dystrophy caused by a single gamma-sarcoglycan mutation. Am J Hum Genet. 1996;59(5):1040‐1047.
23.
Ben HamidaMFardeauMAttiaN. Severe childhood muscular dystrophy affecting both sexes and frequent in Tunisia. Muscle Nerve. 1983;6(7):469‐480.
24.
AmburgeyKMcNamaraNBennettLRMcCormickMEAcsadiGDowlingJJ. Prevalence of congenital myopathies in a representative pediatric United States population. Ann Neurol. 2011;70(4):662‐665.
25.
WittingNWerlauffUDunoMVissingJ. Phenotypes, genotypes, and prevalence of congenital myopathies older than 5 years in Denmark. Neurol Genet. 2017;3(2):e140‐e140.
26.
Pagola-LorzIVicenteEIbáñezB, et al.Epidemiological study and genetic characterization of inherited muscle diseases in a northern Spanish region. Orphanet J Rare Dis. 2019 Dec;14(1):276.
27.
HuangKBiF-FYangH. A systematic review and meta-analysis of the prevalence of congenital myopathy. Front Neurol.2021;12:761636.
28.
ColomboIScotoMManzurAY, et al.Congenital myopathies: natural history of a large pediatric cohort. Neurology. 2015;84(1):28‐35.
29.
MurphySMLauraMFawcettK, et al.Charcot-Marie-Tooth disease: frequency of genetic subtypes and guidelines for genetic testing. J Neurol Neurosurg Psychiatry. 2012;83(7):706‐710.
30.
NelisEVan BroeckhovenCDe JongheP, et al.Estimation of the mutation frequencies in Charcot-Marie-Tooth disease type 1 and hereditary neuropathy with liability to pressure palsies: a European collaborative study. Eur J Hum Genet. 1996;4(1):25‐33.
31.
CookAGiuntiP. Friedreich’s ataxia: clinical features, pathogenesis and management. Br Med Bull. 2017;124(1):19‐30.
32.
MonaniUR. Spinal muscular atrophy: a deficiency in a ubiquitous protein; a motor neuron-specific disease. Neuron. 2005;48(6):885‐896.
33.
McMonaglePWebbSHutchinsonM. The prevalence of “pure” autosomal dominant hereditary spastic paraparesis in the island of Ireland. J Neurol Neurosurg Psychiatry. 2002;72(1):43‐46.
34.
CoutinhoPRuanoLLoureiroJL, et al.Hereditary ataxia and spastic paraplegia in Portugal: a population-based prevalence study. JAMA Neurol. 2013;70(6):746‐755.
35.
ErichsenAKKohtJStray-PedersenAAbdelnoorMTallaksenCME. Prevalence of hereditary ataxia and spastic paraplegia in southeast Norway: a population-based study. Brain. 2009;132(Pt 6):1577‐1588.
36.
BraschinskyMLuusS-MGross-PajuKHaldreS. The prevalence of hereditary spastic paraplegia and the occurrence of SPG4 mutations in Estonia. Neuroepidemiology. 2009;32(2):89‐93.
37.
EngelAG. Genetic basis and phenotypic features of congenital myasthenic syndromes. Handb Clin Neurol. 2018;148:565‐589.
