History

Fact Explanation
Usually occurs in males. Rarely in females. [1] This is an X linked recessive disorder. Thus presence of abnormal X chromosome causes the disease in male. But in females either both X chromosomes have to be affected or lyonization of the normal X chromosome has to occur, where the X chromosome with abnormal gene will be active leading to manifestation of symptoms. [1][2][14]
Muscle cramps/ Myalgia [3][4] Maybe induced by activity. [3]
Abnormal/ waddling/ Trendelenburg gait. [4] Due to proximal muscle weakness. Abnormal gait manifest around 10-15 years of age, which is a later presentation than what is seen in Duchenne muscular dystrophy. [4]
Thigh muscle wasting Generalized progressive atrophy occurs, but thigh muscle wasting could be the only sign because quadriceps myopathy can occur in isolation. [3]
Contractures of ankles, knees, hips and then joints of the upper body [12] This occur due to replacement of elastin with scar tissue and results in reduced mobility of the joint. [12]
Bulky calf 'muscles'. This is now believed to be due to increased number of muscle fibers and its branches which may later undergo fibrosis. [13] Seen at the age of 15-20 years. [4]
Difficulty in climbing stairs and standing up. [4][9] Begins in the 3rd decade of life. [4] May even occur later in life. [9]
Toe walking and lumber lordosis. [10] This is due to weak hip extensors which causes anterior pelvic tilt moving the trunk forward, patient avoids this by lumber lordosis. Weak hip extensors also cause buckling of the knee, to avoid this patient maintains a flexion at knee and planter flexion of ankle. Planter flexion during mid and late stance helps to keep the gravity anterior to knee and keeps it from buckling. [10]
Fatigue, dyspnoea, palpitaion, syncope, ankle oedema, cough [4] Dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmias, heart failure, sudden cardiac death may occur in patients with Becker muscular dystrophy. [4] [1] Symptoms usually begin at 3rd decade of life [4] and is the most common cause of death in Becker muscular dystrophy. [3]
Cognitive impairment. [7] Due to reduced dystrophin in brain leading to central nervous system dysfunction. [5] May occur even in absence of muscle weakness. [6] This can range from severe mental retardation to specific deficits.[7]
Epilepsy.[5] 7.54% of patients with Becker muscular dystrophy have associated epilepsy. Thought to be due to lack of dystrophin in brain leading to neurological dysfunction. [5]
Painless dark colour urine [11] Due to myoglobinuria, usually occurs episodicallly. [3][4]
Macroglossia/ red-green color blindness [8] These have been found in association with Becker muscular dystrophy in some patients. [8]
Presence of family history This is an X linked recessive disorder, thus, a family history compatigle with X linked disorder will be present. [3]
References
  1. FUJII K, MINAMI N et al. Homozygous female Becker muscular dystrophy. American Journal of Medical Genetics Part A. 2009 May; Volume 149A, Issue 5, Pages 1052-5. Available from: doi: 10.1002/ajmg.a.32808. Viewed on: 30/03/2014
  2. Centers for Disease Control and Prevention, Division of Human Development and Disability, National Center on Birth Defects and Developmental Disabilities. Atlanta. Last reviewed: February 18, 2014. Viewed on: 31/04/2014 Available from: http://www.cdc.gov/ncbddd/musculardystrophy/inheritance.html
  3. Darras BT, Miller DT, Urion DK. Dystrophinopathies. 2000 Sep 5 [Updated 2011 Nov 23]. In: Pagon RA, Adam MP, Bird TD, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2014. Viewed on: 30/03/2014 Available from: http://www.ncbi.nlm.nih.gov/books/NBK1119/
  4. FINSTERER Josef, STOLLBERGER Claudia. Cardiac involvement in Becker muscular dystrophy. Canadian Journal of Cardiology. Oct 2008; Volulme 24, Issue 10, Pages 786–792. Viewed on: 30/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2643160/
  5. GOODWIN F, MUNTONI F, DUBOWITZ V. Epilepsy in Duchenne and Becker muscular dystrophies. European Journal of Paediatric Neurology. 1997; Volume 1, Issue 4, Pages 115-9. Viewed on: 30/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/10728205
  6. FURAMURA N, KAWAMOTO K, TAKAHASHI K, FUNAKAWA I, JINNAI K. [Four siblings with becker muscular dystrophy (BMD) manifesting severe mental retardation]. Rinsho Shinkeigaku (Clinical neurology). 2006 Jan; Volume 46, Issue 1, Pages 62-5. Viewed on: 30/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/16541798
  7. DAOUD F, ANGEARD N, DEMERRE B et al. Analysis of Dp71 contribution in the severity of mental retardation through comparison of Duchenne and Becker patients differing by mutation consequences on Dp71 expression. Human Molecular Genetics. 2009 Oct 15; Volume 18, Issue 20, Pages 3779-94. Available from: doi: 10.1093/hmg/ddp320. Viewed on: 30/03/2014
  8. FU HD , TANG XF, GUO YP. Becker muscular dystrophy. Chinese Medical Journal. 1989 May; Volume 102, Issue 5, Paages 373-7. Viewed on: 30/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/2509161
  9. UJIKE H, TOMITA J, KURODA S, OTSUKI S, ARAHATA K. A rare case of adult-onset Becker muscular dystrophy diagnosed by dystrophin staining. No To Shinkei(Brain and nerve). 1991 Oct; Volume 43, Issue 10, Pages 975-9. Viewed on: 31/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/1724729
  10. ROSSI Roger, ALEXANDER Michael, CUCCURULLO Sara. Neuromuscular Disease in Children. In: CUCCURULLO S ed. Physical Medicine and Rehabilitation Board Review. New York: Demos Medical Publishing; 2004. Viewed on: 31/03/2014. Available from: http://www.ncbi.nlm.nih.gov/books/NBK27251/
  11. THAKKER PB, SHARMA A. Becker muscular dystrophy: an unusual presentation. Archieve of Diseases in Childhood. Jul 1993; Volume 69, Issue 1, Pages 158–159. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1029438/?page=1
  12. Becker Muscular Dystrophy. Muscular dystophy association of New Zealand Inc. Last updated April 2010. Viewed on: 31/03/2014 Available from: http://www.mda.org.nz/media/1181/Becker%20Muscular%20Dystrophy%20April10.pdf
  13. SASAOKA T, IMAMURA M, ARAISHI K. Pathological analysis of muscle hypertrophy and degeneration in muscular dystrophy in gamma-sarcoglycan-deficient mice. Neuromuscular Disorder. 2003 Mar; Volume 13, Issue 3, Pages 193-206. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/12609501
  14. SYBERT Virginia P., Lyonization, National Foundation for Ectodermal Dysplasias. [Viewed on: 01/04/2014] Available from: http://nfed.org/uploads/Lyonization.pdf

Examination

Fact Explanation
Patient maybe unable to walk and maybe wheelchair bound. [1] This occurs usually at the age of 16 years. [1]
Pseudo hypertrophy of the calves. This is now believed to be due to increased number of muscle fibers and its branches [2] rather than due to fatty infiltration of the calves' as believed earlier. This may later undergo fibrosis. [2]
Flexion contractures of the ankles, knees, elbows. [1] Occurs later in the course of disease. [1]
Reduced muscle power in proximal than in distal group of limb muscles. [1] Weak quadriceps femoris could be the only positive sign too. This is usually symmetric and continuous monitoring of the power will show progressively worsening weakness. [1]
Power of neck flexors are preserved. [1] Unlike in Duchenne muscular dystrophy in which the neck flexors are also affected. [1]
Positive Gower's sign. Due to the proximal muscle weakness when the child is asked to stand up from supine or sitting position, child first roll onto prone position, with upper and lower limbs extended. Then the trunk's weight mainly borne by upper limb, the body is pushed backwards over the extended legs. Then the hands are placed on the knees to extend the hip and the child climbs on himself till he is in erect position. [5] This sign is not specific to Becker muscular dystrophy and is seen in all diseases associated with pelvic girdle muscle weakness. [5]
Cardiovascular examination. [3] It is essential to perform cardiovascular examination since Becker muscular dystrophy is associated with cardiac involvement and it is the most common cause of morbidity and mortality of these patients. [1] Look for features of heart failure- difficulty breathing, ankle edema, elevated JVP, increased pulse rate, reduced blood pressure, displaced diffuse apex, crepitations in lungs on auscultation owing to pulmonary edema. [4]
References
  1. Darras BT, Miller DT, Urion DK. Dystrophinopathies. 2000 Sep 5 [Updated 2011 Nov 23]. In: Pagon RA, Adam MP, Bird TD, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2014. Viewed on: 30/03/2014 Available from: http://www.ncbi.nlm.nih.gov/books/NBK1119/
  2. SASAOKA T, IMAMURA M, ARAISHI K. Pathological analysis of muscle hypertrophy and degeneration in muscular dystrophy in gamma-sarcoglycan-deficient mice. Neuromuscular Disorder. 2003 Mar; Volume 13, Issue 3, Pages 193-206. Viewed on: 31/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12609501
  3. FINSTERER Josef, STOLLBERGER Claudia. Cardiac involvement in Becker muscular dystrophy. Canadian Journal of Cardiology. Oct 2008; Volulme 24, Issue 10, Pages 786–792. Viewed on: 30/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2643160/
  4. LONGMORE Murray, WILKINSON Ian B. et al. Oxford handbook of clinical medicine. 8th edition. Oxford: Oxford university press 2010.
  5. CHANG Richard F., MUBARAK Scott J. Pathomechanics of Gowers’ Sign: A Video Analysis of a Spectrum of Gowers’ Maneuvers. Clinical Orthopedic Related Researches. Jul 2012; Volume 470, Issue 7, Pages 1987–1991. Available fom: doi: 10.1007/s11999-011-2210-6 Viewed on: 01/04/2014. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369091/#!po=75.0000

Differential Diagnoses

Fact Explanation
Duchenne muscular dystrophy. Age of presentation is much earlier than in Becker, and may present with motor developmental delay. [1] While onset of symptoms in Duchenne muscular dystrophy is 10.5 +/- 7.2 years, in Becker muscular dystrophy it is 2.3 +/- 13, therefore there is an overlap of 18.42% at the age of 4 years.[4] This is due to active muscle degeneration occurring much earlier (about 10 years earlier) in Duchenne than in Becker muscular dystrophy. [2]
Limb-Girdle muscular dystrophy DNA analysis would help to differentiate this from Becker in which dystrophin gene deletion can be demonstrated. [3]
Kugelberg-Welander disease DNA analysis would help to differentiate this from Becker in which dystrophin gene deletion can be demonstrated. [3]
Facioscapulohumeral dystrophy Usually have facial and shoulder girdle weakness but also can present with upper limb or lower limb weakness. Unlike in Becker muscular dystrophy weakness is asymmetrical and cardiac involvement is usually absent. [5][6]
Congenital myopathies. Symptoms start very early in life, in around few months of life, unlike in Becker and about 35% become ventilatory dependent or succumb to illness by the age of 11 years,[7] unlike in Becker muscular dystrophy in which this would be the age when initial symptoms start to manifest.
References
  1. Darras BT, Miller DT, Urion DK. Dystrophinopathies. 2000 Sep 5 [Updated 2011 Nov 23]. In: Pagon RA, Adam MP, Bird TD, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2014. Viewed on: 30/03/2014 Available from: http://www.ncbi.nlm.nih.gov/books/NBK1119/
  2. ZATZ M, RAPAPORT D, VAINZOF M et al. Serum creatine-kinase (CK) and pyruvate-kinase (PK) activities in Duchenne (DMD) as compared with Becker (BMD) muscular dystrophy. Journal of Neurological Science. 1991 Apr; Volume 102, Issue 2, Pages 190-6. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/2072118
  3. LAING NG, MEARS ME, THOMAS HE et al. Differentiation of Becker muscular dystrophy from limb-girdle muscular dystrophy and Kugelberg-Welander disease using a cDNA probe. Medical Journal of Australia. 1990 Mar 5; Volume 152, Issue 5, Pages 270-1. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/2255288
  4. LEAL Alvarez M, SIFUENTES Hernandez PM, PEREZ-ZUNO JA. Differential diagnosis of Becker and Duchenne muscular dystrophy Gaceta Medica de Mexico. 1994 Nov-Dec; Volume 130, Issue 6, Pages 454-8. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/7557060
  5. HASSAN A, JONES LK Jr, MILONE M, KUMAR N. Focal and other unusual presentations of facioscapulohumeral muscular dystrophy. Muscle Nerve. 2012 Sep; Volume 46, Issue 3, Pages 421-5. Available from: doi: 10.1002/mus.23358. Viewed on: 31/03/2014
  6. RIVIERE GV, de VOOGT WG, de VISSER M. The heart in Becker muscular dystrophy, facioscapulohumeral dystrophy, and Bethlem myopathy. Muscle Nerve. 1992 May; Volume 15, Issue 5, Pages 591-6. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/1584251
  7. WEISS K, SHAPIRA Y, GLICK B, LERMAN-SAGIE T et al. Congenital myopathies in Israeli families. Journal of Child Neurology. 2007 Jun; Volume 22, Issue 6, Pages732-6. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/17641259

Investigations - for Diagnosis

Fact Explanation
Immunostaining of biopsy muscle [3] Staining of dystrophin isoform is patchy due to reduced dystrophin. This is due to deletions/ duplications or point mutations of dystrophin gene. [1]
Western blot for dystrophin in biopsy of skeletal muscle [5] Both immunofluorescence detections and western blot give compatible results and are of high value in detection of Becker muscular dystrophy. [5]
PCR of dystrophin Becker muscular dystrophy occur due to deletion/ duplication of dystrophin gene which occurs in about two thirds of patients, this is via PCR. [6][7]
Ultrasound scan of the calves. [2] Abnormal echo intensities of the muscle may occur due to fat infiltration of the muscle causing pseudo hypertrophy of the calf. Both absolute and pseudo hypertrophy of the calves have been observed in Becker muscular dystrophy. [2]
Creatinine kinase.[3] Elevated levels are seen in affected individuals, 5 times higher than the normal value. [3] Estimation of creatine kinase is superior to estimation of pyruvate kinase in detection of Becker muscular dystrophy. [4]
References
  1. FINSTERER Josef, STOLLBERGER Claudia. Cardiac involvement in Becker muscular dystrophy. Canadian Journal of Cardiology. Oct 2008; Volume 24, Issue 10, Pages 786–792. PMCID: PMC2643160. Viewed on: 30/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2643160/
  2. REIMERS CD, SCHLOTTER B, EICKE BM, WITT TN. Calf enlargement in neuromuscular diseases: a quantitative ultrasound study in 350 patients and review of the literature. Journal of Neurological Sciences. 1996 Nov; Volume 143, Issue 1-2, Pages 46-56. Viewed on: 31/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/8981297
  3. UJIKE H, TOMITA J, KURODA S, OTSUKI S, ARAHATA K. A rare case of adult-onset Becker muscular dystrophy diagnosed by dystrophin staining. No To Shinkei(Brain and nerve). 1991 Oct; Volume 43, Issue 10, Pages 975-9. Viewed on: 31/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/1724729
  4. ASTON JP, KINGSTON HM, RAMASAMY I, WALTERS EG, STANSBIE D. Plasma pyruvate kinase and creatine kinase activity in Becker muscular dystrophy. Journal of Neurological Science. 1984 Sep; Volume 65, Issue 3, Pages 307-14. Viewed on: 31/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/6491692
  5. VOIT T, STUETTGEN P, CREMER M, GOEBEL HH. Dystrophin as a diagnostic marker in Duchenne and Becker muscular dystrophy. Correlation of immunofluorescence and western blot. Neuropediatrics. 1991 Aug; Volume 22, Issue 3, Pages 152-62. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/1944822
  6. MANSFIELD ES, ROBERTSON JM et al. Duchenne/Becker muscular dystrophy carrier detection using quantitative PCR and fluorescence-based strategies. American Journal of Medical Genetics. 1993 Dec 15; Volume 48, Issue 4, Pages200-8. Viewed on: 31/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/7510932.
  7. KIM UK, CHAE JJ, LEE SH, LEE CC, NAMKOONG Y. Molecular diagnosis of Duchenne/Becker muscular dystrophy by polymerase chain reaction and microsatellite analysis. Molecules and Cells. 2002 Jun 30; Volume 13, Issue 3, Pages 385-8. Viewed on: 31/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12132577

Investigations - Followup

Fact Explanation
Elevated CK-MB [1] Shows cardiac damage.[1] Cardiac involvement is not associated with clinical severity of illness, there for careful monitoring is necessary even if muscle weakness is only mild. [2]
ECG May reveal arrythmias/ cardiac damage [1]
2D echocardiogram Anatomy of the myocardium can be viewed, hypertrophied/ dilated cardiomyopathy can be seen and ejection fraction could be calculated. [1]
Thallium myocardial scintigraphy Reduced myocardial perfusion. [1]
Cardiac magnetic resonance imaging (cMRI), Hypertrophied/ dilated myocardium, fibrosis can be visualised. [1]
Magnetic resonance spectroscopy (MRS) Shows reduced dystrophin.
Endomyocardial biopsy Fibrosis, hypertrabeculation of left ventricle, atrophic myocardiocytes can be seen. [1]
References
  1. FINSTERER Josef, STOLLBERGER Claudia. Cardiac involvement in Becker muscular dystrophy. Canadian Journal of Cardiology. Oct 2008; Volulme 24, Issue 10, Pages 786–792. PMCID: PMC2643160. Viewed on: 30/03/2014. Availalble from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2643160/
  2. SAKATA C, YAMADA H, SUNOHARA N, ARAHATA K, NONAKA I. Cardiomyopathy in Becker muscular dystrophy. Rinsho Shinkeigaku. 1990 Sep; Volume 30, Issue 9, Pages 952-5. Viewed on: 30/03/2014. Available from: http://www.ncbi.nlm.nih.gov/pubmed/2265504

Investigations - Screening/Staging

Fact Explanation
Creatine kinase of patient mother and brothers. [1][2] About 30 % of the carriers will have 2 to 10 times higher levels of creatine kinase. [1]
DNA analysis of the mother of the affected child. [2] Becker muscular dystrophy is and X linked recessive disorder, thus mainly seen in males. Since all the males inherit the X chromosome from their mother, any deletion/ of the gene may also be present in mother's chromosome (as seen in two third of the cases), one third of the cases are spontaneous mutations. [3] Dystrophin specific DNA probe and creatine kinase is used to calculate the risk of being a carrier of affected gene. This is helpful to genetic council the parents regarding having another child/ deciding whether other siblings maybe affected. [2]
Prenatal diagnosis-Chorionic villus sampling. [4] Can be done in carriers who want to have children of their own. [4]
References
  1. Darras BT, Miller DT, Urion DK. Dystrophinopathies. 2000 Sep 5 [Updated 2011 Nov 23]. In: Pagon RA, Adam MP, Bird TD, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2014. Viewed on: 30/03/2014 Available from: http://www.ncbi.nlm.nih.gov/books/NBK1119/
  2. SARFARAZI M, NEWCOMBE RG, WILLIS N, HARPER PS. Carrier detection in Becker muscular dystrophy using creatine kinase estimation and DNA analysis. Clinical Genetics. 1985 Apr; Volume 27, Issue 4, Pages 383-91. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/3995787
  3. Centers for Disease Control and Prevention, Division of Human Development and Disability, National Center on Birth Defects and Developmental Disabilities. Atlanta. Last reviewed: February 18, 2014. Viewed on: 31/04/2014 Available from: http://www.cdc.gov/ncbddd/musculardystrophy/inheritance.html
  4. ESSEN Van AJ, KNEPPERS AL, HOUT Van Der AH et al. The clinical and molecular genetic approach to Duchenne and Becker muscular dystrophy: an updated protocol. Journal of Medical Genetics. Oct 1997; Volume 34, Issue 10, Pages 805–812. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1051085/?page=6

Management - General Measures

Fact Explanation
Multidisciplinary approach towards symptomatic treatment. Physicians, occupational therapists, counselors, orthopedic surgeons and pediatricians together have to make patient specific decisions to manage the patients. [4]
Genetic counselling. Becker muscular dystrophy is an X linked recessive disorder, thus affects males more than females and two thirds of affected males inherit the deformed gene from the mother while one third develop spontaneous mutation. [1] Deformed gene of the mother can be diagnosed by DNA analysis following screening with creatine kinase levels, together the carrier state can be detected and if mother is a carrier 50% of sons will be affected. Father do not carry the gene defect to the son, but all the daughters will be carriers.[1] [2]
Pharmocological therapy for cardiomyopathy. Has been proved to improve cardiac status of the patient. Patients with cardiac abnormality usually survive up to 30 years of age at which they need cardiac transplant or may succumb to illness. [3]
Invasive and noninvasive mechanical ventilation/ Implanted cardiac devices.[4] If the intercostal muscles become weak there could be a respiratory compensation which could be supported by artificial ventilation.
References
  1. Centers for Disease Control and Prevention, Division of Human Development and Disability, National Center on Birth Defects and Developmental Disabilities. Atlanta. Last reviewed: February 18, 2014. Viewed on: 31/04/2014 Available from: http://www.cdc.gov/ncbddd/musculardystrophy/inheritance.html
  2. SARFARAZI M, NEWCOMBE RG, WILLIS N, HARPER PS. Carrier detection in Becker muscular dystrophy using creatine kinase estimation and DNA analysis. Clinical Genetics. 1985 Apr; Volume 27, Issue 4, Pages 383-91. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/3995787
  3. DOING AH, RENLUND DG, SMITH RA. Becker muscular dystrophy-related cardiomyopathy: a favorable response to medical therapy. Journal of Heart and Lung Transplantation. 2002 Apr; Volume 21, Issue 4, Pages 496-8. Viewed on: 31/03/2014 Available from: http://www.ncbi.nlm.nih.gov/pubmed/11927228
  4. LEUNG Doris G, WAGNER Kathryn R. Therapeutic advances in muscular dystrophy. Annals of Neurology. Sep 2013; Volume 74, Issue 3, Pages 404–411. Viewed on: 31/03/2014. Available from: doi: 10.1002/ana.23989

Management - Specific Treatments

Fact Explanation
Currently there is no specific therapy for Becker muscular dystrophy but a mode of gene therapy is being widely investigated. [1] Eteplirsen, drisapersen- still undergoing clinical trials. They are in phase II / III of clinical trials and seen to have increased expression of dystrophin. [2]
References
  1. CHAMBERLAIN Jeffrey S. Gene therapy of muscular dystrophy. Human Molecular Genetics Volume 11, Issue 20. Pages 2355-2362. Viewed on: 31/03/2014. Available from: doi: 10.1093/hmg/11.20.2355
  2. LEUNG Doris G, WAGNER Kathryn R. Therapeutic advances in muscular dystrophy. Annals of Neurology. Sep 2013; Volume 74, Issue 3, Pages 404–411. Available from: doi: 10.1002/ana.23989 Viewed on: 31/03/2014