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[Gene expression in lactate dehydrogenase-A subunit deficiency].
H Miyajima1, T Shimizu, E Kaneko
1First Department of Medicine, Hamamatsu University School of Medicine.
Rinsho Shinkeigaku = Clinical Neurology
|October 1, 1992
Summary
This study identifies a genetic mutation causing muscle pain and stiffness. A 20 bp deletion in the LDH-A gene leads to an inactive enzyme, impacting muscle function.
Area of Science:
- Biochemistry
- Genetics
- Molecular Biology
Background:
- Lactate dehydrogenase (LDH) is crucial for energy metabolism in muscle.
- Defects in LDH can lead to exercise intolerance and muscle symptoms.
Observation:
- A patient presented with exercise-induced muscle pain and stiffness, with a family history of similar symptoms.
- Muscle LDH activity was severely reduced (<8% of normal), with an abnormal isoenzyme pattern (only B4).
- Blood lactate levels did not increase with anaerobic exercise, but pyruvate levels rose significantly.
Findings:
- Genetic analysis revealed a 20 bp deletion in exon 6 of the LDH-A gene, causing a frame-shift mutation.
- This mutation results in a truncated, enzymatically inactive LDH-A subunit.
- LDH-A mRNA was transcribed, but produced a non-functional protein in muscle fibers.
Implications:
- This genetic defect impairs anaerobic glycolysis, leading to exercise-induced muscle symptoms.
- Understanding this mutation provides insight into LDH function and muscle energy pathways.
- Potential for targeted genetic therapies or diagnostic approaches for similar conditions.