Related Experiment Videos
A new point mutation associated with mitochondrial encephalomyopathy
K J Morten1, J M Cooper, G K Brown
1Department of Paediatrics, University of Oxford, John Radcliffe Hospital, UK.
Abstract:
Point mutations in the mitochondrial gene tRNA leucine(UUR) have been associated with maternally inherited mitochondrial myopathies including the MELAS syndrome (Mitochondrial Myopathy Encephalopathy Lactic acidosis and Stroke-like episodes). We describe a further mutation in tRNA leucine(UUR) in a patient with mitochondrial encephalomyopathy, pigmentary retinopathy, dementia, hypoparathyroidism and diabetes mellitus. The mutation was heteroplasmic in the proband's blood (30%) and muscle (76%); it was present at high levels in the proband's affected mother (50% in muscle), and at low levels (< 10%) in blood, muscle and fibroblasts of an unaffected sister. The mutation was not found in 121 normal controls or 35 other patients with mitochondrial disorders. The mutation is at a highly conserved position in the tRNA molecule, close to the 3,243 mutation which is associated with more than 80% of MELAS cases. Further more, both mutations lie within a possible transcriptional control region. This finding adds further support to the evidence that mutations in this region and in other mitochondrial tRNA genes may cause disease.
Insights
A novel mutation in the mitochondrial tRNA leucine(UUR) gene was identified in a patient with mitochondrial encephalomyopathy. This finding expands the known genetic causes of maternally inherited mitochondrial disorders.
Area of Science:
- Genetics
- Molecular Biology
- Neurology
Background:
- Mitochondrial myopathies, including MELAS syndrome, are often linked to point mutations in the mitochondrial tRNA leucine(UUR) gene.
- Maternally inherited mitochondrial diseases result from mutations in the mitochondrial genome.
Observation:
- A novel mutation in the mitochondrial tRNA leucine(UUR) gene was identified in a patient presenting with mitochondrial encephalomyopathy, pigmentary retinopathy, dementia, hypoparathyroidism, and diabetes mellitus.
- This mutation exhibited heteroplasmy in the patient's blood (30%) and muscle (76%), with varying levels in affected and unaffected family members.
- The mutation was absent in healthy controls and other patients with mitochondrial disorders.
Findings:
- The identified mutation is located at a highly conserved position within the tRNA molecule, near the common MELAS-associated mutation at position 3,243.
- Both mutations are situated within a potential transcriptional control region of the mitochondrial genome.
- The mutation's presence in affected individuals and varying levels of heteroplasmy suggest its role in disease pathogenesis.
Implications:
- This discovery broadens the spectrum of mutations in the mitochondrial tRNA leucine(UUR) gene associated with mitochondrial encephalomyopathies.
- It reinforces the hypothesis that mutations within this specific region and other mitochondrial tRNA genes can lead to complex clinical presentations.
- Further research into this mutation could elucidate specific pathomechanisms and inform diagnostic strategies for mitochondrial disorders.