Muscular dystrophy

==Diagnosis==
The diagnosis of muscular dystrophy is based on the results of [[muscle biopsy]], increased [[creatine phosphokinase]] (CpK3), [[electromyography]], and [[genetic testing]]. A physical examination and the patient's medical history will help the doctor determine the type of muscular dystrophy. Specific muscle groups are affected by different types of muscular dystrophy.<ref>{{cite web|url=https://www.nichd.nih.gov/health/topics/musculardys/conditioninfo/pages/diagnosed.aspx|title=NIH /How is muscular dystrophy diagnosed?|date=2015|website=NIH.gov|publisher=NIH|access-date=10 April 2016|url-status=live|archive-url=https://web.archive.org/web/20160407124113/https://www.nichd.nih.gov/health/topics/musculardys/conditioninfo/pages/diagnosed.aspx|archive-date=7 April 2016}}</ref>

An MRI can be used to assess the white matter of the nervous system and measure the merosin levels in young boys. An absence of merosin in young boys will result with neurological deficits and changes in the white matter.<ref>{{Cite journal |last=Emery |first=Alan EH |date=2002-02-23 |title=The muscular dystrophies |url=https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(02)07815-7/fulltext |journal=The Lancet |language=English |volume=359 |issue=9307 |pages=687–695 |doi=10.1016/S0140-6736(02)07815-7 |issn=0140-6736 |pmid=11879882|s2cid=31578361 }}</ref>

===Classification===
{| class="wikitable"
|-
! Disorder name
![[OMIM]]
! Gene
!Inheritance pattern
!Age of onset
!Muscles affected
! Description
|-
|'''[[Becker muscular dystrophy]]'''
|{{OMIM|300376||none}}
|''[[Dystrophin|DMD]]''
|[[X-linked recessive inheritance|XR]]
|Childhood
|Distal limbs progressing to generalised weakness
| A less severe variant of [[Duchenne muscular dystrophy]],<ref name="2006 report to Congress">[http://www.ninds.nih.gov/about_ninds/groups/mdcc/md_care_implementation.pdf May 2006 report to Congress] {{webarchive|url=https://web.archive.org/web/20140405023440/http://www.ninds.nih.gov/about_ninds/groups/mdcc/md_care_implementation.pdf|date=2014-04-05}} on Implementation of the [[MD CARE Act]], as submitted by Department of Health and Human Service's [[National Institutes of Health]]</ref> affects predominantly boys.
|-
|'''[[Congenital muscular dystrophy]]'''
| Multiple
| Multiple
|[[Autosomal dominant inheritance|AD]], [[Autosomal recessive inheritance|AR]]
|At birth
|Generalised weakness
| Symptoms include general muscle weakness and possible joint deformities. Disease progresses slowly, and lifespan is shortened.
Congenital muscular dystrophy includes several disorders with a range of symptoms. Muscle degeneration may be mild or severe. Problems may be restricted to [[skeletal muscle]], or muscle degeneration may be paired with effects on the brain and other organ systems.<ref>{{EMedicine|article|1180214|Congenital Muscular Dystrophy|clinical}}</ref>

Several forms of the congenital muscular dystrophies are caused by defects in proteins thought to have some relationship to the dystrophin-glycoprotein complex and to the connections between muscle cells and their surrounding cellular structure. Some forms of congenital muscular dystrophy show severe brain malformations, such as [[lissencephaly]] and [[hydrocephalus]].<ref name="2006 report to Congress" />
|-
|'''[[Duchenne muscular dystrophy]]'''
|{{OMIM|310200||none}}
|''[[Dystrophin|DMD]]''
|[[X-linked recessive inheritance|XR]]
|Childhood
|Distal limbs progressing to generalised weakness, involving respiratory muscles
| The most common childhood form of muscular dystrophy, affects predominantly boys (mild symptoms may occur in female carriers). Characterised by progressive muscle wasting. Clinical symptoms become evident when the child begins walking. By age 10, the child may need braces and by age 12, most patients are unable to walk.<ref name="MedlinePlusEncyclopedia000705">{{Cite web|url=https://medlineplus.gov/ency/article/000705.htm|title=Duchenne muscular dystrophy: MedlinePlus Medical Encyclopedia|website=medlineplus.gov|language=en|access-date=2017-03-14|url-status=live|archive-url=https://web.archive.org/web/20170405014656/https://medlineplus.gov/ency/article/000705.htm|archive-date=2017-04-05}}</ref> Typical lifespans range from 15 to 45.<ref name="MedlinePlusEncyclopedia000705" /> Sporadic mutations in this gene occur frequently.<ref>{{cite web |url=http://patient.info/health/duchenne-muscular-dystrophy-leaflet |title=Duchenne Muscular Dystrophy. What is muscular dystrophy? &#124; Patient |website=Patient.info |date=2016-04-15 |access-date=2017-03-14 |url-status=live |archive-url=https://web.archive.org/web/20161202094502/http://patient.info/health/duchenne-muscular-dystrophy-leaflet |archive-date=2016-12-02 }}</ref>
|-
|'''[[Distal muscular dystrophy]]'''
|{{OMIM|254130||none}}
|''[[Dysferlin|DYSF]]''
|[[Autosomal dominant inheritance|AD]], [[Autosomal recessive inheritance|AR]]
|20–60 years
|Distal muscles in hands, forearms and lower legs
| Progress is slow and not life-threatening.<ref>{{cite book |last1=Udd |first1=Bjarne |chapter=Distal muscular dystrophies |title=Handbook of Clinical Neurology |volume=101 |pages=239–62 |year=2011 |pmid=21496636 |doi=10.1016/B978-0-08-045031-5.00016-5 |isbn=978-0-08-045031-5 }}</ref>

Miyoshi myopathy, one of the distal muscular dystrophies, causes initial weakness in the calf muscles, and is caused by defects in the same gene responsible for one form of [[limb–girdle muscular dystrophy]].<ref name="2006 report to Congress" />
|-
|'''[[Emery–Dreifuss muscular dystrophy]]'''
|Multiple
|Multiple
|[[X-linked recessive inheritance|XR]], [[Autosomal dominant inheritance|AD]], [[Autosomal recessive inheritance|AR]]
|Childhood, early teenage years
|Distal limb muscles, limb-girdle, heart
| Symptoms include muscle weakness and wasting, starting in the distal limb muscles and progressing to involve the limb–girdle muscles. Most patients also have cardiac conduction defects and arrhythmias.<ref>{{cite web |url=http://www.omim.org/entry/310300 |archive-url=https://web.archive.org/web/20170310151551/http://www.omim.org/entry/310300 |url-status=dead |archive-date=2017-03-10 |title=OMIM Entry - # 310300 - EMERY-DREIFUSS MUSCULAR DYSTROPHY 1, X-LINKED; EDMD1 |website=Omim.org |access-date=2017-03-14 }}</ref><ref>{{cite web |url=https://ghr.nlm.nih.gov/condition/emery-dreifuss-muscular-dystrophy |title=Emery-Dreifuss muscular dystrophy - Genetics Home Reference |website=Ghr.nlm.nih.gov |date=2017-03-07 |access-date=2017-03-14 |url-status=live |archive-url=https://web.archive.org/web/20170312112220/https://ghr.nlm.nih.gov/condition/emery-dreifuss-muscular-dystrophy |archive-date=2017-03-12 }}</ref>
|-
|'''[[Facioscapulohumeral muscular dystrophy]]'''
|{{OMIM|158900||none}}
|''[[DUX4]]''
|[[Autosomal dominant inheritance|AD]]
|Adolescence
|Face, shoulders, upper arms, progressing to other muscles
| Causes progressive weakness, initially in the muscles of the face, shoulders, and upper arms. Additional muscles are often affected.<ref>{{cite web |url=https://ghr.nlm.nih.gov/condition/facioscapulohumeral-muscular-dystrophy |title=facioscapulohumeral muscular dystrophy - Genetics Home Reference |website=Ghr.nlm.nih.gov |access-date=2017-03-14 |url-status=live |archive-url=https://web.archive.org/web/20170324203921/https://ghr.nlm.nih.gov/condition/facioscapulohumeral-muscular-dystrophy |archive-date=2017-03-24 }}</ref> Affected individuals can become severely disabled, with 20% requiring a wheelchair by age 50.<ref name="FSHD 2016 Review Article">{{cite journal |last1=Statland |first1=JM |last2=Tawil |first2=R |title=Facioscapulohumeral Muscular Dystrophy. |journal=Continuum (Minneapolis, Minn.) |date=December 2016 |volume=22 |issue=6, Muscle and Neuromuscular Junction Disorders |pages=1916–1931 |doi=10.1212/CON.0000000000000399 |pmid=27922500|pmc=5898965 }}</ref> 30% of cases involve spontaneous mutations.<ref name="FSHD 2016 Review Article" /> Penetrance and severity seem to be lower in females compared to males.<ref name="FSHD 2016 Review Article" /><ref>{{cite web |url=https://www.nlm.nih.gov/medlineplus/ency/article/000707.htm |title=Facioscapulohumeral muscular dystrophy: MedlinePlus Medical Encyclopedia |website=Nlm.nih.gov |date=2017-03-09 |access-date=2017-03-14 |url-status=live |archive-url=https://web.archive.org/web/20160704222205/https://www.nlm.nih.gov/medlineplus/ency/article/000707.htm |archive-date=2016-07-04 }}</ref>
|-
|'''[[Limb–girdle muscular dystrophy]]'''
| Multiple
| Multiple
|[[Autosomal dominant inheritance|AD]], [[Autosomal recessive inheritance|AR]]
|Any
|Upper arms and legs
| The person normally leads a normal life with some assistance. Rare cardiopulmonary complications can be life-threatening.<ref>{{cite book|last=Jenkins|first=Simon P.R.|title=Sports Science Handbook:I - Z.|year=2005|publisher=Multi-Science Publ. Co.|location=Brentwood, Essex|isbn=978-0906522-37-0|page=121}}</ref>
|-
|'''[[Myotonic muscular dystrophy]]'''
|{{OMIM|160900||none}}{{brk}}{{OMIM|602668||none}}
|''[[Myotonin-protein kinase|DMPK]]''{{brk}}''[[CNBP]]''
|[[Autosomal dominant inheritance|AD]]
|Adulthood
|Skeletal muscles, heart, other muscle groups
| Presents with [[myotonia]] (delayed relaxation of muscles), as well as muscle wasting and weakness.<ref name="Turner">{{cite journal |last1=Turner |first1=C. |last2=Hilton-Jones |first2=D. |title=The myotonic dystrophies: diagnosis and management |journal=Journal of Neurology, Neurosurgery & Psychiatry |volume=81 |issue=4 |pages=358–67 |year=2010 |pmid=20176601 |doi=10.1136/jnnp.2008.158261 |s2cid=2453622 |url=http://jnnp.bmj.com/content/jnnp/81/4/358.full.pdf |doi-access=free }}</ref> Varies in severity and manifestations and affects many body systems in addition to skeletal muscles, including the heart, endocrine organs, and eyes.<ref>{{cite book|chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK1165/|title=Myotonic Dystrophy Type 1 - GeneReviews® - NCBI Bookshelf|website=Ncbi.nlm.nih.gov|access-date=2017-03-14|url-status=live|archive-url=https://web.archive.org/web/20170118123627/https://www.ncbi.nlm.nih.gov/books/NBK1165/|archive-date=2017-01-18|chapter=Myotonic Dystrophy Type 1|publisher=University of Washington, Seattle|year=1993|pmid=20301344 |last1=Bird |first1=T. D. |last2=Adam |first2=M. P. |last3=Everman |first3=D. B. |last4=Mirzaa |first4=G. M. |last5=Pagon |first5=R. A. |last6=Wallace |first6=S. E. |author7=Bean LJH |last8=Gripp |first8=K. W. |last9=Amemiya |first9=A. }}</ref>
|-
|'''[[Oculopharyngeal muscular dystrophy]]'''
|{{OMIM|164300||none}}
|''[[PABPN1]]''
|[[Autosomal dominant inheritance|AD]], rarely [[Autosomal recessive inheritance|AR]]
|40–50 years
|Eye muscles, face, throat, pelvis, shoulders
|
|}