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Muscle fiber degeneration in distal myopathy with rimmed vacuole formation
N Murakami1, Y Ihara, I Nonaka
1Department of Ultrastructural Research, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan.
Abstract:
In 11 patients with distal myopathy with rimmed vacuole formation (DMRV), a well-known autosomal recessively inherited disorder, the rimmed vacuole formation appears to be the main pathological change accounting for the progressive muscle fiber degeneration. To gain a better understanding of the pathophysiology of the vacuole formation, we applied Congo red and immunohistochemical stains to muscle biopsies from these patients and the results were compared with those of patients with inclusion body myositis (IBM). The vacuoles in DMRV contained Congophilic amyloid material and deposits immunoreactive for beta-amyloid protein, both the NH2 and COOH termini of beta-amyloid protein precursor, ubiquitin, and tau protein. These results were similar to those seen in our present cases of IBM as well as in previously reported cases. Therefore, there may be no pathogenetic differences in the formation of rimmed vacuoles in DMRV and IBM. Nevertheless, the degenerative process involved in rimmed vacuole formation in various diseases may share a common pathogenetic mechanism with that in amyloid-plaque formation in Alzheimer's disease brain as has been proposed previously.
Insights
Distal myopathy with rimmed vacuole formation (DMRV) shares pathological similarities with inclusion body myositis (IBM). Vacuoles in DMRV contain amyloid material, suggesting a common mechanism in muscle degenerative diseases.
Area of Science:
- Neurology
- Pathology
- Genetics
Background:
- Distal myopathy with rimmed vacuole formation (DMRV) is an autosomal recessive disorder characterized by progressive muscle degeneration.
- Rimmed vacuole formation is the primary pathological hallmark in DMRV, driving muscle fiber breakdown.
Purpose of the Study:
- To investigate the pathophysiology of vacuole formation in DMRV.
- To compare the pathological features of DMRV with inclusion body myositis (IBM).
Main Methods:
- Muscle biopsies from 11 DMRV patients were analyzed.
- Congo red staining and immunohistochemical stains were applied.
- Results were compared with IBM cases.
Main Results:
- Vacuoles in DMRV biopsies contained Congophilic amyloid material.
- Deposits immunoreactive for beta-amyloid precursor protein (APP), ubiquitin, and tau were identified.
- These findings were similar to those observed in IBM.
Conclusions:
- The formation of rimmed vacuoles in DMRV and IBM may share common pathogenetic mechanisms.
- The degenerative process in rimmed vacuole formation might be linked to amyloid plaque formation in Alzheimer's disease.