Unexpected myopathy associated with a mutation in MYBPC3 and misplacement of the cardiac myosin-binding protein C
- Homa Tajsharghi1,
- Trond P Leren2,
- Saba Abdul-Hussein1,
- Mar Tulinius3,
- Leif Brunvand4,
- Hilde M Dahl4,
- Anders Oldfors1,*
- 1 Institute of Biomedicine, University of Gothenburg, Sweden;
- 2 Oslo University Hospital, Department of Medical Genetics, Norway;
- 3 Institute of Clinical Sciences, University of Gothenburg, Sweden;
- 4 Ullevål University Hospital, Department of Pediatrics, Sweden
- Correspondence to: Anders Oldfors, Department of Pathology, Institute of Biomedicine, University of Gothenburg, Sahlgrenska University Hospital, Department of Pathology, Gothenburg, 413c 5, Sweden; anders.oldfors{at}gu.se
- Received 23 August 2009
- Accepted 12 October 2009
- Published Online First 26 October 2009
Abstract
Background: Myosin binding protein C (MyBPC) is essential for the structure of the sarcomeres in striated muscle. There is one cardiac specific isoform and two skeletal muscle specific isoforms. Mutations in MYBPC3 encoding the cardiac isoform cause cardiomyopathy.
We have identified an infant with fatal cardiomyopathy due to a homozygous mutation, p.R943X, in MYBPC3. The patient also had an unexpected skeletal myopathy.
Results: The patient expressed the cardiac specific MyBPC isoform in skeletal muscle at transcript and protein levels. Numerous muscle fibers expressing the mutant cardiac isoform showed structural abnormalities with disorganization of sarcomeres and depletion of myosin thick filaments.
Conclusions: The surprising identification of a skeletal myopathy in this patient was due to aberrant expression of mutant cardiac MyBPC in skeletal muscle.
