Heteroplasmic Mutant Load Differences in Mitochondrial DNA-Associated Leigh Syndrome

Area of Science:

• Genetics and Molecular Biology
• Neuroscience
• Mitochondrial Biology

Background:

• Mitochondrial DNA (mtDNA)-associated Leigh syndrome is a severe neurological disorder.
• The relationship between mutant load and disease severity in Leigh syndrome is not fully understood.
• Investigating heteroplasmic mutant load distribution is crucial for understanding Leigh syndrome phenotypes.

Purpose of the Study:

• To investigate the distribution of heteroplasmic mutant loads for different mitochondrial DNA mutations in Leigh syndrome patients.
• To explore the relationship between specific mtDNA mutations and their corresponding mutant loads.
• To analyze genotype-phenotype correlations in a single-center cohort.

Main Methods:

• Next-generation sequencing was used to identify mtDNA mutations in 31 Leigh syndrome patients.
• Quantitative analysis of mtDNA reads determined heteroplasmic mutant loads.
• Patients were categorized based on mutations in six genes and 10 nucleotides.

Main Results:

• Twenty-seven out of 31 patients had known pathogenic mtDNA mutations.
• MT-ATP6 was the most frequent mutation (13 patients), followed by MT-ND3 (7) and MT-ND5 (4).
• MT-ATP6 mutations showed significantly higher mutant loads compared to MT-ND3 and MT-ND5.

Conclusions:

• The study highlights significant heteroplasmic diversity in mtDNA-associated Leigh syndrome.
• Findings provide insights into the phenotypic expression threshold and genotype-phenotype correlation.
• Results may guide the development of targeted treatments for Leigh syndrome.