Atormac
Neurology India
menu-bar5 Open access journal indexed with Index Medicus
  Users online: 2020  
 Home | Login 
About Editorial board Articlesmenu-bullet NSI Publicationsmenu-bullet Search Instructions Online Submission Subscribe Videos Etcetera Contact
  Navigate Here 
 Search
 
  
 Resource Links
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
    Article in PDF (431 KB)
    Citation Manager
    Access Statistics
    Reader Comments
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this Article
   References

 Article Access Statistics
    Viewed2453    
    Printed24    
    Emailed0    
    PDF Downloaded116    
    Comments [Add]    

Recommend this journal

 


 
Table of Contents    
NI FEATURE: THE EDITORIAL DEBATE II-- PROS AND CONS
Year : 2017  |  Volume : 65  |  Issue : 5  |  Page : 969-970

Muscular dystrophies: An Indian scenario


Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

Date of Web Publication6-Sep-2017

Correspondence Address:
Atchayaram Nalini
Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/neuroindia.NI_733_17

Rights and Permissions



How to cite this article:
Nalini A, Polavarapu K, Preethish-Kumar V. Muscular dystrophies: An Indian scenario. Neurol India 2017;65:969-70

How to cite this URL:
Nalini A, Polavarapu K, Preethish-Kumar V. Muscular dystrophies: An Indian scenario. Neurol India [serial online] 2017 [cited 2019 Oct 20];65:969-70. Available from: http://www.neurologyindia.com/text.asp?2017/65/5/969/214075


Muscular dystrophies are a heterogeneous group of hereditary degenerative primary muscle disorders characterized by symmetrical/asymmetrical, progressive, proximal or proximo-distal muscle weakness with hypertrophy and/or wasting and with characteristic dystrophic changes on muscle histopathology. Formerly, these muscular dystrophies were subdivided based on clinical and pathological criteria, but are currently classified primarily by the mutations affecting genes encoding various skeletal muscle proteins.[1] However, for their proper characterization, an accurate clinical evaluation with the identification of topography of the skeletal muscle involvement, along with knowledge of the mode of inheritance, age at onset, pattern of progression etc., and the associated systemic involvement of respiratory, cardiac, bulbar and ocular muscles is crucial. Phenotypic characterisation is essential before subjecting these patients to an advanced genetic testing and/or invasive muscle biopsies. The muscular dystrophies are grouped based on the major clinical/mutation pattern and the age at onset as Duchenne and Becker muscular dystrophies (DMD and BMD), facioscapulohumeral dystrophy (FSHD), myotonic dystrophy (DM1),  Emery-Dreifuss muscular dystrophy More Details (EDMD), limb-girdle muscular dystrophies (LGMDs) and congenital muscular dystrophies (CMDs). The presence of genetic defects has led to further classification of the heterogeneous groups like LGMDs, CMDs, and different phenotypes have been linked as allelic variants of the same gene suggesting the complex genotype-phenotype heterogeneity of these dystrophies.[2] Dystrophinopathies due to mutations in the DMD gene located at Xp21 chromosome include the most common childhood-onset muscular dystrophy, DMD, a milder form of BMD, and the rare X-linked dilated cardiomyopathy. From an epidemiological view point, DMD is the most common muscular dystrophy of childhood with an estimated incidence rate ranging from 1 in 3500 to 1 in 5000 boys. The milder form BMD is about 1/5th less frequent than DMD.[1] As one of the well-studied muscular dystrophies, the diagnosis and management of DMD has changed rapidly during the last decade resulting in a better quality of life with prolonged ambulation and an increased lifespan of the affected boys, with an early genetic diagnosis and standard of care involving oral steroids, supportive management and periodical monitoring of cardiac function.[3] Advances in genetic diagnosis has reduced the need for an invasive muscle biopsy. Nevertheless, histopathological confirmation is less frequently required due to limitations of the current molecular diagnostic methods. For a long period, multiplex polymerase chain reaction (mPCR) remained the standard diagnostic test which could detect 98% of the exon deletions in about 60% of the patients with DMD.[4] However, during the past decade, multiplex ligation-dependent probe amplification (MLPA) technique has emerged as a more effective method for the detection of both deletions and duplication in all 79 exons of the DMD gene with an increased accuracy.[5] Currently in India, mPCR is still the common test followed, with MLPA being performed only in a few selected higher centres and genetic laboratories. When clinical diagnosis of DMD is accurate, MLPA detection rate can be more than 80%.[6] Furthermore, deletion/duplication detection with accurate breakpoint information contributes to a better genotype-phenotype correlation between DMD and the milder BMD phenotypes based on the reading frame rule.[7] For the MLPA negative cases, direct gene sequencing of the DMD gene is required for point mutations and is being rarely done in India. Next-generation sequencing is emerging as a rapid diagnostic method which can be developed as a unified genetic testing modality for detecting more than 90-95% of cases before contemplating a biopsy. Current emphasis of research is on novel therapeutic trials involving exon skipping, nonsense suppression and gene transfer techniques.[8] Detailed genotyping with next-generation sequencing (NGS), natural history studies, as well as an improved carrier and prenatal testing are the need of the hour to impart trial readiness and also to reduce the disease burden in India. Myotonic dystrophy (DM1) is the most common form in adults with an estimated point prevalence of 1:9400.[9] Presently, qualitative genetic testing (TP-PCR) is available and affordable for DM1 in India; however, studies on large cohorts and phenotype-genotype correlates are lacking. LGMDs have a worldwide prevalence rate of 1 in 14,500–45,000 with the autosomal recessive (AR) forms being more common than the dominant ones.[10] Current available studies on AR limb girdle muscular dystrophies (ARLGMDs) from India are mainly hospital-based with limited genetic information. In the largest study published from India, 300 cases were evaluated at NIMHANS, Bangalore over a span of 2 years (2010-2012).[11] A total of 226 unrelated patients were confirmed to have muscular dystrophy on biopsy and 199/226 were classified into various ARLGMD subtypes based on immunohistochemistry (IHC) and western blotting (WB) studies. In contrast to the western populations, where calpainopathy (LGMD 2A) is reported as the most common subtype, dysferlinopathy (LGMD 2B) was found to be most prevalent (33.3%) in this study, but patients predominantly from the southern states of India were recruited. Other common phenotypes of ARLGMD's included alpha-dystroglycanopathies (LGMD 2I and 2K), sarcoglycanopathies (LGMD 2C-F) and calpainopathy (LGMD 2A), in that order. However, this classification was based only on the histopathological data which needs further confirmation by genetic studies for more accurate prevalence information. Large scale genetic studies on ARLGMDs are lacking in India, except a few short series on calpainopathy, sarcoglycanopathies and dysferlinopathy.[12],[13]

Congenital muscular dystrophies (CMD) constitute a rare infancy/childhood onset heterogeneous group of muscular dystrophies with an estimated prevalence of less than 0.89/100000, and disorders related to laminin α-2 (merosin) and collagen VI deficiencies being the most common forms.[14] The only study from India on CMD's included 56 histopathologically confirmed cases comprising of MDC1A = 9; MDC1B = 13; MDC1C = 3; Unclassified = 31.[15] FSHD is one of the most prevalent adult muscular dystrophies with a worldwide prevalence ranging from 1:15,000 to 1:20,000. FSHD genetic testing is not widely available in India and one publication with genetic confirmation has 12 patients of FSHD1 included.[16]

In the comprehensive article by Shri Ram,[17] describing the global trend of publications in muscular dystrophy research, it is noted that the last decade has witnessed a surge in the publications globally. Although there has been a significant increase in publication on muscular dystrophies among Indian scientists, the contribution to the global number is only a meagre 1.7%. There are no major studies addressing the genetic mutation patterns, phenotype-genotype correlates and epidemiological studies among the various muscular dystrophies. The majority of the research publications appear to be restricted to a few tertiary care centres. Thus, India needs to develop an integrated multicenter approach for the diagnosis and documentation of various muscular dystrophies among the huge Indian population.

 
  References Top

1.
Wicklund MP. The muscular dystrophies. Contin Minneap Minn 2013;19:1535-70.  Back to cited text no. 1
    
2.
Mercuri E, Muntoni F. Muscular dystrophies. Lancet Lond Engl 2013;381:845-60.  Back to cited text no. 2
    
3.
Rahbek J, Werge B, Madsen A, Marquardt J, Steffensen BF, Jeppesen J. Adult life with Duchenne muscular dystrophy: Observations among an emerging and unforeseen patient population. Pediatr Rehabil 2005;8:17-28.  Back to cited text no. 3
    
4.
Beggs AH, Koenig M, Boyce FM, Kunkel LM. Detection of 98% of DMD/BMD gene deletions by polymerase chain reaction. Hum Genet 1990;86:45-8.  Back to cited text no. 4
    
5.
Schwartz M, Dunø M. Improved molecular diagnosis of dystrophin gene mutations using the multiplex ligation-dependent probe amplification method. Genet Test 2004;8:361-7.  Back to cited text no. 5
    
6.
Manjunath M, Kiran P, Preethish-Kumar V, Nalini A, Singh RJ, Gayathri N. A comparative study of mPCR, MLPA, and muscle biopsy results in a cohort of children with Duchenne muscular dystrophy: A first study. Neurol India 2015;63:58.  Back to cited text no. 6
[PUBMED]  [Full text]  
7.
Vengalil S, Preethish-Kumar V, Polavarapu K, Mahadevappa M, Sekar D, Purushottam M, et al. Duchenne muscular dystrophy and Becker muscular dystrophy confirmed by multiplex ligation-dependent probe amplification: Genotype-phenotype correlation in a large cohort. J Clin Neurol Seoul Korea 2017;13:91-7.  Back to cited text no. 7
    
8.
Flanigan KM. Duchenne and Becker muscular dystrophies. Neurol Clin 2014;32:671-88, viii.  Back to cited text no. 8
    
9.
Thornton CA. Myotonic dystrophy. Neurol Clin 2014;32:705-19, viii.  Back to cited text no. 9
    
10.
Murphy AP, Straub V. The classification, natural history and treatment of the limb girdle muscular dystrophies. J Neuromuscul Dis 2015;2:S7-19.  Back to cited text no. 10
    
11.
Nalini A, Polavarapu K, Sunitha B, Kulkarni S, Gayathri N, Bharath MS, et al. A prospective study on the immunophenotypic characterization of limb girdle muscular dystrophies 2 in India. Neurol India 2015;63:548.  Back to cited text no. 11
[PUBMED]  [Full text]  
12.
Khadilkar SV, Chaudhari CR, Dastur RS, Gaitonde PS, Yadav JG. Limb-girdle muscular dystrophy in the Agarwals: Utility of founder mutations in CAPN3 gene. Ann Indian Acad Neurol 2016;19:108-11.  Back to cited text no. 12
[PUBMED]  [Full text]  
13.
Khadilkar SV, Singh RK, Hegde M, Urtizberea A, Love DR, Chong B. Spectrum of mutations in sarcoglycan genes in the Mumbai region of western India: High prevalence of 525del T. Neurol India 2009;57:406.  Back to cited text no. 13
[PUBMED]  [Full text]  
14.
Norwood FLM, 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 J Neurol 2009;132:3175-86.  Back to cited text no. 14
    
15.
Nagappa M, Atchayaram N, Narayanappa G. A large series of immunohistochemically confirmed cases of congenital muscular dystrophy seen over a period of one decade. Neurol India 2013;61:481.  Back to cited text no. 15
  [Full text]  
16.
Tamhankar PM, Phadke SR. Clinical profile and molecular diagnosis in patients of facioscapulohumeral dystrophy from Indian subcontinent. Neurol India 2010;58:436.  Back to cited text no. 16
[PUBMED]  [Full text]  
17.
Ram S. Global muscular dystrophy research: A 25-year bibliometric perspective. Neurol India 2017;65. 993-1000.  Back to cited text no. 17
    




 

Top
Print this article  Email this article
   
Online since 20th March '04
Published by Wolters Kluwer - Medknow