Nemaline myopathy (NM) is a congenital neuromuscular disorder with heterogeneous clinical signs such as muscle weakness, affecting humans, seldom dogs and cats. For human NM, several causative gene mutations have been identified. The hallmark of this disease is the presence of sarcoplasmic inclusions (nemaline rods) in skeletal muscle fibres, which can be visualised in sections of muscle specimens. Ultrastructurally, an enlargement and streaming of the Z lines can be detected. Here, the case of two 10-week-old female Border collie littermates with progressive gait dysfunction, muscle stiffness and exercise intolerance, which were euthanased because of poor prognosis, is described. Histology of formalin-fixed paraffin-embedded muscle samples revealed sarcoplasmic rods visible in tissue sections stained with haematoxylin and eosin, the Gomori trichrome and the phosphotungstic acid haematoxylin stain. In electron microscopy, the rods were confirmed as streaming of the Z lines. Therefore, a congenital NM was diagnosed.
- inherited disease
- muscle disorders
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Contributors MD and SK made the autopsy and helped with the manuscript. KB is the clinician who did the clinical/neurological examination and further chemical and clinical tests as well as the video. MH and TS supervised the necropsy cases and helped with the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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