Global InformationBethlem myopathy information
| Bethlem myopathy | |
|---|---|
| Other names | Muscular dystrophy, limb-girdle, autosomal dominant 5, (LGMDD5); Muscular dystrophy, limb-girdle, autosomal recessive 22, (LGMDR22); Ehlers–Danlos syndrome, myopathic type (EDSMYP) |
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| Bethlem myopathy has an autosomal dominant pattern of inheritance (autosomal recessive form exists as well[1]). | |
Bethlem myopathy is predominantly an autosomal dominant myopathy, classified as a congenital form of limb-girdle muscular dystrophy.[2] There are two types of Bethlem myopathy, based on which type of collagen is affected.[3]
Bethlem myopathy 1 (BTHLM1) is caused by a mutation in one of the three genes coding for type VI collagen.[4][3] These include COL6A1, COL6A2, and COL6A3.[5][3] It is typically autosomal dominant, though uncommonly can be autosomal recessive.[3]
Bethlem myopathy 2 (BTHLM2), formerly known as myopathic-type Ehlers–Danlos syndrome, is caused by a mutation on the COL12A1 gene coding for type XII collagen.[3] It is autosomal dominant.[3]
In 2017, an international workshop proposed a redefined criteria and naming system for limb-girdle muscular dystrophies. Bethlem myopathy 1 (collagen VI) was included into the proposed list and renamed LGMDD5 for autosomal dominant mutations and LGMDR22 for recessive mutations. Bethlem myopathy 2 (collagen XII) was not addressed.[2]
Gowers's sign, toe walking, multiple contractures of the joints (especially the fingers: 'Bethlem sign'), skin abnormalities, and muscle weakness (proximal more than distal) are typical signs and symptoms of the disease. Initially, in early childhood, there may also be joint laxity. There is no cardiac involvement in either Bethlem myopathy 1 or 2, which helps to differentiate it from Emery–Dreifuss muscular dystrophy.[6] Currently there is no cure for the disease and symptomatic treatment is used to relieve symptoms and improve quality of life.[7]
Bethlem myopathy may be diagnosed based on clinical examinations and laboratory tests may be recommended. Genetic testing for known pathological variants is preferred. In the case of a VUS, testing of dermal fibroblast culture is used for an accurate diagnosis.[6]
Bethlem myopathy 1 is a rare disease, affecting about 1 in 200,000 people.[8] Bethlem myopathy 2 is an ultra-rare disease, affecting less than 1 in 1,000,000 people.[9]
The condition was described by J. Bethlem and G. K. van Wijngaarden in 1976.[10]
- ^ RESERVED, INSERM US14 -- ALL RIGHTS. "Orphanet: Bethlem myopathy". www.orpha.net. Retrieved 23 December 2017.
{{cite web}}: CS1 maint: numeric names: authors list (link) - ^ a b Straub, Volker; Murphy, Alexander; Udd, Bjarne; LGMD workshop study group (August 2018). "229th ENMC international workshop: Limb girdle muscular dystrophies - Nomenclature and reformed classification Naarden, the Netherlands, 17-19 March 2017". Neuromuscular Disorders. 28 (8): 702–710. doi:10.1016/j.nmd.2018.05.007. ISSN 1873-2364. PMID 30055862.
- ^ a b c d e f "Phenotypic Series - PS158810 Bethlem myopathy - PS158810 - 4 Entries". OMIM - Online Mendelian Inheritance in Man.
- ^ Jobsis GJ, Boers JM, Barth PG, de Visser M (1999). "Bethlem myopathy: a slowly-progressive congenital muscular dystrophy with contractures". Brain. 122 (4): 649–655. doi:10.1093/brain/122.4.649. PMID 10219778.
- ^ Lampe AK, Bushby KM (September 2005). "Collagen VI related muscle disorders". J. Med. Genet. 42 (9): 673–85. doi:10.1136/jmg.2002.002311. PMC 1736127. PMID 16141002.
- ^ a b Bertini, Enrico; D'Amico, Adele; Gualandi, Francesca; Petrini, Stefania (December 2011). "Congenital muscular dystrophies: a brief review". Seminars in Pediatric Neurology. 18 (4): 277–288. doi:10.1016/j.spen.2011.10.010. ISSN 1558-0776. PMC 3332154. PMID 22172424.
- ^ "Bethlem myopathy | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program". rarediseases.info.nih.gov. Retrieved 2020-10-19.
- ^ Cite error: The named reference
Okada2007was invoked but never defined (see the help page). - ^ "Myopathic EDS (mEDS)". The Ehlers Danlos Society. Retrieved 2023-05-01.
- ^ "Entry - #158810 - BETHLEM MYOPATHY 1; BTHLM1 - OMIM". Online Mendelian Inheritance in Man. Retrieved 2023-09-15.