Using electrophysiologic techniques, researchers were able to show clear abnormalities in the neuromuscular junctions of the patients, as evidenced by increased jitter or jitter with blocking of muscle fibers.
Researchers also found evidence that SLC25A1 may be required for normal neuromuscular junction formation by looking at the effects of reduced expression of SLC25A1 in zebrafish embryos. Anatomically, while the muscle fibers appeared normal, presynaptic motor axon terminals were shortened and grew erratically, with no evidence of complete synapse formation. They also saw structural changes in the brain and heart, which mirrored abnormalities seen in humans.
"It is still not clear how deficits in a mitochondrial citrate carrier result in neuromuscular junction defect," comments Dr. Lochmller. However, while mutations in SLC25A1 may prove to only be a rare cause of CMS, he and his co-investigators advise clinicians that should a patient show fatigable weakness, it may be appropriate to test for SLC25A1 mutations and consider screening for cardiac and metabolic defects should these mutations be found.
"We aimed to identify the underlying molecular defect in this family ever since we met them first in clinic more than 20 years ago," adds co-investigator Kate Bushby, MD, Professor of Neuromuscular Genetics, Institute of Genetic Medicine, MRC Centre for Neuromuscular Diseases, Newcastle University. "We are pleased that latest sequencing technology has resolved this long-standing diagnostic puzzle, which helps us in counseling and treating them more effectively".
Congenital myasthenic syndromes (CMS) are a group of inherited neuromusc
|Contact: Daphne Watrin|