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Understanding the Changes in Mitochondrial Morphology through Dynamic and Three-dimensional Fluorescence Micrographs
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Mitochondrial "dysmorphology" in variant classification.

Hanan E Shamseldin1, Amal Alhashem2, Brahim Tabarki2

  • 1Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.

Human Genetics
|November 9, 2021
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Summary
This summary is machine-generated.

Mitochondrial morphology changes can help classify genetic variants of uncertain significance (VUS) in mitochondrial disorders. Observing specific mitochondrial shapes aided in diagnosing patients with VUS in MFF and DNAJA3 genes.

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Area of Science:

  • Genetics and Genomics
  • Cell Biology
  • Molecular Medicine

Background:

  • Mitochondrial disorders present diagnostic challenges, with exome sequencing improving precision.
  • Interpreting variants of uncertain significance (VUS) remains a major hurdle in diagnosing mitochondrial disorders.
  • The role of mitochondrial morphology in classifying VUS is currently unknown.

Purpose of the Study:

  • To investigate whether specific mitochondrial morphological changes can aid in the classification of VUS.
  • To explore the utility of mitochondrial dysmorphology in reaching a molecular diagnosis for rare genetic disorders.

Main Methods:

  • Described two families (four patients) with VUS in genes affecting mitochondrial fission-fusion balance.
  • Analyzed mitochondrial morphology in patients with VUS in MFF and DNAJA3.
  • Correlated observed mitochondrial phenotypes with variant classifications.

Main Results:

  • A VUS in MFF (fission factor) was associated with impaired mitochondrial fission and an over-tubular morphology.
  • A VUS in DNAJA3 was associated with fragmented mitochondria, consistent with known deficiency states.
  • Specific mitochondrial phenotypes enabled upgrading the classification of these VUS.

Conclusions:

  • Mitochondrial dysmorphology, specifically changes in shape, can be a valuable tool for interpreting VUS.
  • In select cases, observing mitochondrial morphology aids in the molecular diagnosis of mitochondrial disorders.
  • This approach enhances diagnostic precision for challenging genetic conditions affecting mitochondria.