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Condition report · Musculoskeletal

Polyglucosan Body Myopathy 1 (RBCK1)

A rare inherited muscle disease in which abnormal sugar deposits build up in muscle and heart, causing weakness and heart muscle disease, sometimes with immune problems. It is caused by changes in both copies of the RBCK1 gene.

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The condition we analyse

Polyglucosan Body Myopathy 1 With or Without Immunodeficiency

Autosomal recessive

This condition is caused by changes in both copies of RBCK1, which makes HOIL-1, part of a protein complex that regulates inflammation and immune signalling. Loss of HOIL-1 leads to build-up of abnormal glycogen (polyglucosan) in muscle cells.

Signs and symptoms

Progressive weakness of the limb muscles and heart muscle disease, which can lead to heart failure, are the main features. Some people also have recurrent infections and episodes of inflammation. Muscle biopsy shows polyglucosan deposits.

What a diagnosis changes

Regular heart monitoring with heart failure treatment is important. Physiotherapy supports mobility, and immunology input is needed when infections or inflammation occur. Genetic counselling is recommended; parents are usually carriers, each future child has a risk of being affected, and carrier testing can be offered to relatives.

Genes analysed

Also known as

PGBM1; polyglucosan body myopathy type 1; polyglucosan body myopathy, early-onset, with or without immunodeficiency

MONDO:0014389OMIM 615895Orphanet 397937MedGen 863042Sources: [1][3][2]

References

  1. Hedberg-Oldfors C, Oldfors A, 2016. Polyglucosan storage myopathies. Molecular aspects of medicine
  2. Phadke R, Hedberg-Oldfors C, Scalco RS, Lowe DM, Ashworth M, Novelli M et al., 2021. RBCK1-related disease: A rare multisystem disorder with polyglucosan storage, auto-inflammation, recurrent infections, skeletal, and cardiac myopathy-Four additional patients and a review of the current literature. Journal of inherited metabolic disease
  3. Sun Q, Xie Z, Song L, Fu D, 2024. A case of polyglucosan body myopathy caused by an RBCK1 gene variant and literature review. Molecular genetics & genomic medicine

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