Facioscapulohumeral muscular dystrophy type 2 (FSHD 2)

Written and reviewed by Dr Ibrahim Imam, Consultant Neurologist. Last reviewed .

Facioscapulohumeral muscular dystrophy type 2 (FSHD 2). FSHD2 accounts for 5-10% of phenotypic FSHD. Fully referenced neurology checklist.

Genetics

  • FSHD2 accounts for 5-10% of phenotypic FSHD
  • It is most frequently sporadic but some cases are familial
  • It is caused by mutations in the SMCHD1 and DNMT3B gene mutations on chromosome 18p
  • These genes are D4Z4 chromatin modifiers
  • The mutations result in D4Z4 hypomethylation
  • SMCHD1 is also involved in BAMS syndrome
  • FSHD2 can also be caused by LRIF1 gene mutation
  • Monosomy 18p (18p deletion syndrome) is also a risk factor
  • Other genetic risk factors are CAPN3 and VCP

Clinical features

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Acronyms

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References

  1. de Greef JC, Lemmers RJLF, Camano P, et al. Clinical features of facioscapulohumeral muscular dystrophy 2. Neurology 2010; 75:1548-1554.
  2. Lemmers RJ, van den Boogaard ML, van der Vliet PJ, et al. Hemizygosity for SMCHD1 in facioscapulohumeral muscular dystrophy type 2: consequences for 18p deletion syndrome. Hum Mutat 2015; 36:679-683.
  3. Leidenroth A, Sorte SH, Gilfillan G, Ehrlich M, Lyle R, Hewitt JE. Diagnosis by sequencing: correction of misdiagnosis from FSHD2 to LGMD2A by whole-exome analysis. Eur J Hum Genet 2012; 20:999-1003.
  4. Hamanaka K, Šikrová D, Mitsuhashi S, et al. Homozygous nonsense variant in LRIF1 associated with facioscapulohumeral muscular dystrophy. Neurology 2020; 94:e2441-e2447.
  5. Mah JK, Chen YW. A pediatric review of facioscapulohumeral muscular dystrophy. J Pediatr Neurol 2018; 16:222-231. 
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