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Related Concept Videos

Animal Mitochondrial Genetics02:59

Animal Mitochondrial Genetics

Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...
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Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. Mutations can be characterized in a number of different ways: whether and how they alter the amino acid sequence of the protein, whether they occur over a small or large area of DNA, and whether they occur in somatic cells or germline cells.
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Translation Produces the Building Blocks of Life
Translation01:31

Translation

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Translation Produces the Building Blocks of Life

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Updated: Jul 7, 2026

Modeling Mitochondrial Disease Using Brain Organoids: A Focus on Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes
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A novel tRNA(Val) mitochondrial DNA mutation causing MELAS.

Kurenai Tanji1, Petra Kaufmann, Ali B Naini

  • 1Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, NY, USA. kt8@columbia.edu

Journal of the Neurological Sciences
|March 4, 2008
PubMed
Summary
This summary is machine-generated.

Researchers identified a new mitochondrial DNA mutation in the tRNA(Val) gene causing MELAS syndrome in a 37-year-old woman. This finding expands the known genetic causes of mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes.

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Area of Science:

  • Genetics
  • Neurology
  • Mitochondrial Biology

Background:

  • Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a common mitochondrial disorder.
  • It is primarily caused by mutations in mitochondrial DNA (mtDNA), with the A3243G mutation in the tRNA(Leu(UUR)) gene being the most frequent (approx. 80% of cases).
  • At least 15 distinct mtDNA mutations are linked to MELAS, highlighting genetic heterogeneity.

Purpose of the Study:

  • To report a novel mitochondrial DNA mutation associated with MELAS.
  • To characterize the clinicopathological phenotype of a patient with this novel mutation.
  • To compare this case with other rare tRNA(Val) mutations linked to MELAS.

Main Methods:

  • Genetic analysis of mitochondrial DNA (mtDNA).
  • Clinical evaluation and phenotyping of the patient.
  • Literature review and comparison with previously reported cases of tRNA(Val) mutations.

Main Results:

  • Identification of a novel tRNA(Val) mutation in a 37-year-old woman presenting with MELAS.
  • Detailed description of the patient's clinical manifestations and pathological findings.
  • Comparison of the patient's phenotype with those of other individuals harboring rare tRNA(Val) mutations.

Conclusions:

  • The study identifies a new genetic cause for MELAS, expanding the spectrum of mtDNA mutations responsible for this condition.
  • The findings contribute to understanding the genotype-phenotype correlation in MELAS, particularly for rare tRNA(Val) mutations.
  • This case underscores the importance of comprehensive genetic analysis in diagnosing MELAS, especially in atypical presentations.