Neuropathy associated with mitochondrial disorders

Area of Science:

• Neurology
• Mitochondrial Biology
• Pathology

Background:

• Mitochondrial myopathies and hereditary neuropathies often involve peripheral nerves.
• Mitochondrial DNA deletions are implicated in the pathogenesis of mitochondrial diseases.

Purpose of the Study:

• To investigate and characterize mitochondrial alterations in peripheral nerves across various neuropathies.
• To determine the prevalence and nature of mitochondrial changes in Schwann cells and other peripheral nerve components.

Main Methods:

• Electron microscopy was used for diagnostic evaluation of 280 unselected neuropathy cases.
• Morphometric analysis was employed to assess neuropathy in mitochondrial myopathy cases.

Main Results:

• Altered mitochondria were observed in most mitochondrial myopathy cases, all hereditary motor and sensory neuropathy with optic atrophy (HMSN VI) cases, and 25/280 unselected neuropathies.
• Mitochondrial changes in nerves included enlarged mitochondria, distorted cristae, paracrystalline inclusions, and striated cristae, differing from muscle.
• Abnormalities were predominantly in Schwann cells, with occasional perineurial cell involvement.

Conclusions:

• Peripheral nerve mitochondrial alterations are a significant finding in various neuropathies, particularly mitochondrial myopathies and HMSN VI.
• The presence of neuropathy in all mitochondrial myopathy cases suggests a direct role or susceptibility of peripheral neurons.
• Further research is needed to elucidate the direct causal link between mitochondrial dysfunction and neuropathy in these conditions.