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Condition report · Musculoskeletal

Polyglucosan Body Myopathy 2 (GYG1)

An inherited muscle condition that causes progressive weakness, starting in adulthood, due to abnormal glycogen building up in muscle. It is caused by changes in both copies of the GYG1 gene.

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The condition we analyse

Autosomal recessive

Caused by changes in both copies of GYG1, which encodes glycogenin-1, the protein that starts glycogen formation. Abnormal glycogen (polyglucosan) accumulates in muscle fibres.

Signs and symptoms

Progressive weakness of the hip and shoulder muscles, or sometimes of the hands and lower legs, starting in adulthood, is typical. Muscle biopsy shows polyglucosan deposits. The heart muscle can also be affected, causing cardiomyopathy.

What a diagnosis changes

Physiotherapy and mobility support, with heart assessment because some people develop cardiomyopathy. Carrier testing of relatives and genetic counselling are available.

Genes analysed

Also known as

GYG1 polyglucosan body myopathy; PGBM2; polyglucosan body myopathy 2; polyglucosan body myopathy caused by mutation in GYG1

MONDO:0014526OMIM 616199Orphanet 456369MedGen 863889Sources: [2][3][4][1]

References

  1. Hedberg-Oldfors C, Oldfors A, 2016. Polyglucosan storage myopathies. Molecular aspects of medicine
  2. Akman HO, Aykit Y, Amuk OC, Malfatti E, Romero NB, Maioli MA et al., 2016. Late-onset polyglucosan body myopathy in five patients with a homozygous mutation in GYG1. Neuromuscular disorders : NMD
  3. Hedberg-Oldfors C, Mensch A, Visuttijai K, Stoltenburg G, Stoevesandt D, Kraya T et al., 2018. Polyglucosan myopathy and functional characterization of a novel GYG1 mutation. Acta neurologica Scandinavica
  4. Nicolau S, Tracy JA, Pisapia DJ, Tanji K, Milone M, 2024. GYG1: A distal myopathy with polyglucosan bodies. JIMD reports

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