Distal myopathy

Distal myopathy is a group of rare genetic disorders that cause muscle damage and weakness, predominantly in the hands and/or feet. Mutation of many different genes can be causative. Many types involve dysferlin.[1]

Distal myopathy
Other namesDistal muscular dystrophy
Red depicts the preferentially affected areas in distal myopathy.
SpecialtyNeurology, neuromuscular medicine
SymptomsWeakness of hands and/or feet
ComplicationsCardiomyopathy
Usual onsetVariable
DurationLifetime
TypesClassic, myofibrillar myopathy, other
CausesGenetic mutation of various genes
Diagnostic methodGenetic testing, muscle biopsy
FrequencyRare

Signs and symptoms

All of the different types affect different regions of the extremities and can show up as early as 5 years of age to as late as 50 years old. Distal myopathy has slow progress therefore the patient may not know that they have it until they are in their late 40s or 50s.

Miyoshi myopathy affects the posterior muscles of the lower leg, more so than the anterior muscles of the lower leg.[2][3]

Cause
DYSF

The cause of this myopathy is very hard to determine because it can be a mutation in any of at least eight genes and not all are known yet. These mutations can be inherited from one parent, autosomal dominant, or from both parents, autosomal recessive. There are eight known types of distal myopathy.

Types
Classic distal muscular dystrophies
Type Eponym Inheritance OMIM Gene Locus Gene also implicated in:
Late adult-onset type 1[4] Welander AD[5] 604454 TIA1[6] 2p13[7]
Late adult-onset type 2a[5] - Finnish (tibial) Udd AD[5] 600334 TTN[5] 2q31.2
Late adult-onset type 2b[5] Markesbery–Griggs AD[8] ZASP[5] 10q23.2
Early adult-onset type 1[4] Nonaka AR[5] 605820 GNE[5] 9p13.3
Early adult-onset type 2[4] Miyoshi AR[5] 254130 DYSF[5] 2p13.3-p13.1 limb-girdle muscular dystrophy type 2B.[9]
Distal myopathy with anterior tibial onset (DMAT)[10][11] 606768 DMAT can be considered a variant of Miyoshi.
Early adult-onset type 3[4] Laing (Gower) AD[5] 160500 MYH7[5] 14q11.2
AD = autosomal dominant; AR = autosomal recessive
Myofibrillar myopathies classifiable as distal myopathy
Type Eponym Inheritance OMIM Gene Locus Gene also implicated in:
Desmin — adult onset (MFM1)[5]

Hereditary inclusion-body myositis type 1[5]

 AD
αB-crystallin — early - mid adult (MFM2)[5] AD
ZASP— late adult (MFM4)[5] AD
Scapuloperoneal[5] AD
MFM = myofibrillary myopathy; AD = autosomal dominant; AR = autosomal recessive
Other distal muscular dystrophies
Type Eponym Inheritance OMIM Gene Locus Gene also implicated in:
Distal myopathy with vocal cord and pharyngeal weakness[4] AD[5] 606070 MATR3[5] 5q31[5] Amyotrophic lateral sclerosis 21 (ALS21). One study suggests that all cases are ALS, justifying reclassification.[12]

Diagnosis

In terms of diagnosis, Vocal cord and pharyngeal distal myopathy should be assessed via serum CK levels, as well as muscle biopsy of the individual suspected of being afflicted with this condition[13]

Management

As of 2011, no disease modifying treatments are known.[8] Foot drop can be managed with ankle-foot orthoses or surgical tendon transfer,[8] in which the tibialis posterior muscle is repurposed to function as a tibialis anterior muscle. In select types of distal myopathy, evaluation of the heart may be indicated.[8] Scoliosis and contractures can be surgically managed.[8]

References
  1. Murakami N, Sakuta R, Takahashi E, et al. (December 2005). "Early onset distal muscular dystrophy with normal dysferlin expression". Brain Dev. 27 (8): 589–91. doi:10.1016/j.braindev.2005.02.002. PMID 16310593. S2CID 28957231.
  2. Soares CN, de Freitas MR, Nascimento OJ, da Silva LF, de Freitas AR, Werneck LC (December 2003). "Myopathy of distal lower limbs: the clinical variant of Miyoshi". Arq Neuropsiquiatr. 61 (4): 946–9. doi:10.1590/S0004-282X2003000600011. PMID 14762596.
  3. Aoki, Masashi (1 January 1993). "Dysferlinopathy". GeneReviews. PMID 20301480. Retrieved 10 May 2016.
  4. Saperstein, DS; Amato, AA; Barohn, RJ (November 2001). "Clinical and genetic aspects of distal myopathies". Muscle & Nerve. 24 (11): 1440–50. doi:10.1002/mus.1167. PMID 11745945. S2CID 26573674.
  5. Dimachkie, MM; Barohn, RJ (August 2014). "Distal myopathies". Neurologic Clinics. 32 (3): 817–42, x. doi:10.1016/j.ncl.2014.04.004. PMC 4109660. PMID 25037092.
  6. Hackman P, Sarparanta J, Lehtinen S, Vihola A, Evilä A, Jonson PH, Luque H, Kere J, Screen M, Chinnery PF, Åhlberg G, Edsröm L, Udd B (January 2013). "Welander Distal Myopathy Is Caused by a Mutation in the RNA-Binding Protein TIA1". Annals of Neurology. 73 (4): 500–509. doi:10.1002/ana.23831. PMID 23401021. S2CID 13908127.
  7. von Tell D, Bruder CE, Anderson LV, Anvret M, Ahlberg G (August 2003). "Refined mapping of the Welander distal myopathy region on chromosome 2p13 positions the new candidate region telomeric of the DYSF locus". Neurogenetics. 4 (4): 173–7. doi:10.1007/s10048-003-0154-z. PMID 12836053. S2CID 27539044.
  8. Udd, B (2011). Distal muscular dystrophies. Handbook of Clinical Neurology. Vol. 101. pp. 239–62. doi:10.1016/B978-0-08-045031-5.00016-5. ISBN 9780080450315. PMID 21496636.
  9. Illa I (March 2000). "Distal myopathies". J. Neurol. 247 (3): 169–74. doi:10.1007/s004150050557. PMID 10787109. S2CID 39723106. Archived from the original on 2013-02-13.
  10. Liu, J; Aoki, M; Illa, I; Wu, C; Fardeau, M; Angelini, C; Serrano, C; Urtizberea, JA; Hentati, F; Hamida, MB; Bohlega, S; Culper, EJ; Amato, AA; Bossie, K; Oeltjen, J; Bejaoui, K; McKenna-Yasek, D; Hosler, BA; Schurr, E; Arahata, K; de Jong, PJ; Brown RH, Jr (September 1998). "Dysferlin, a novel skeletal muscle gene, is mutated in Miyoshi myopathy and limb girdle muscular dystrophy". Nature Genetics. 20 (1): 31–6. doi:10.1038/1682. PMID 9731526. S2CID 12018395.
  11. Illa, I; Serrano-Munuera, C; Gallardo, E; Lasa, A; Rojas-García, R; Palmer, J; Gallano, P; Baiget, M; Matsuda, C; Brown, RH (January 2001). "Distal anterior compartment myopathy: a dysferlin mutation causing a new muscular dystrophy phenotype". Annals of Neurology. 49 (1): 130–4. doi:10.1002/1531-8249(200101)49:1<130::AID-ANA22>3.0.CO;2-0. PMID 11198284.
  12. Johnson, JO; Pioro, EP; Boehringer, A; Chia, R; Feit, H; Renton, AE; Pliner, HA; Abramzon, Y; Marangi, G; Winborn, BJ; Gibbs, JR; Nalls, MA; Morgan, S; Shoai, M; Hardy, J; Pittman, A; Orrell, RW; Malaspina, A; Sidle, KC; Fratta, P; Harms, MB; Baloh, RH; Pestronk, A; Weihl, CC; Rogaeva, E; Zinman, L; Drory, VE; Borghero, G; Mora, G; Calvo, A; Rothstein, JD; ITALSGEN.; Drepper, C; Sendtner, M; Singleton, AB; Taylor, JP; Cookson, MR; Restagno, G; Sabatelli, M; Bowser, R; Chiò, A; Traynor, BJ (May 2014). "Mutations in the Matrin 3 gene cause familial amyotrophic lateral sclerosis". Nature Neuroscience. 17 (5): 664–666. doi:10.1038/nn.3688. PMC 4000579. PMID 24686783.
  13. Udd, Bjarne (1 January 2011). "Distal muscular dystrophies". Muscular Dystrophies. Handbook of Clinical Neurology. Vol. 101. pp. 239–262. doi:10.1016/B978-0-08-045031-5.00016-5. ISBN 9780080450315. ISSN 0072-9752. PMID 21496636. – via ScienceDirect (Subscription may be required or content may be available in libraries.)

Further reading
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