Extension of the DNAJB2a isoform in a dominant neuromyopathy family

Jaakko Sarparanta, Per Harald Jonson, Jens Reimann, Anna Vihola, Helena Luque, Sini Penttilä, Mridul Johari, Marco Savarese, Peter Hackman, Cornelia Kornblum, Bjarne Udd

Research output: Contribution to journalArticleScientificpeer-review


Recessive mutations in the DNAJB2 gene, encoding the J-domain co-chaperones DNAJB2a and DNAJB2b, have previously been reported as the genetic cause of progressive peripheral neuropathies, rarely involving pyramidal signs, parkinsonism and myopathy. We describe here a family with the first dominantly acting DNAJB2 mutation resulting in a late-onset neuromyopathy phenotype. The c.832 T > G p.(*278Glyext*83) mutation abolishes the stop codon of the DNAJB2a isoform resulting in a C-terminal extension of the protein, with no direct effect predicted on the DNAJB2b isoform of the protein. Analysis of the muscle biopsy showed reduction of both protein isoforms. In functional studies, the mutant protein mislocalized to the endoplasmic reticulum due to a transmembrane helix in the C-terminal extension. The mutant protein underwent rapid proteasomal degradation and also increased the turnover of co-expressed wild-type DNAJB2a, potentially explaining the reduced protein amount in the patient muscle tissue. In line with this dominant negative effect, both wild-type and mutant DNAJB2a were shown to form polydisperse oligomers.

Original languageEnglish
JournalHuman Molecular Genetics
Issue number21
Pages (from-to)3029-3039
Number of pages11
Publication statusPublished - 17 Oct 2023
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 1184 Genetics, developmental biology, physiology
  • 3124 Neurology and psychiatry

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