25: mtDNA discovery in Solve‑RD: phenotype‑driven reanalysis

Ratnaike et al et al., The American Journal of Human Genetics - A semi-automated mtDNA reanalysis pipeline using MToolBox and MitoPhen HPO-based phenotype similarity was applied to the Solve-RD cohort, identifying previously undiagnosed mtDNA variants and adding a 0.4% diagnostic uplift. Key terms: mitochondrial DNA, heteroplasmy, MitoPhen, Solve-RD, phenotype similarity.

Study Highlights:
The authors validated an mtDNA calling and prioritization workflow on 42 pre-solved exomes and then applied it to 10,157 ES/GS datasets from 9,923 individuals in Solve-RD. Automated filtering (heteroplasmy ≥1%, MITOMAP annotation, haplogroup exclusion) prioritized 136 mtDNA variants in 135 undiagnosed individuals. An HPO-based phenotype similarity score from MitoPhen (threshold >0.3) was tested and used to prioritize candidates, capturing 34 of 37 confirmed or likely causative diagnoses. The integrated genotype-phenotype pipeline yielded 37 new confirmed or likely mtDNA diagnoses, a 0.4% diagnostic uplift in this heterogeneous cohort.

Conclusion:
Incorporating structured mtDNA analysis and HPO-based phenotype similarity scoring into ES/GS reanalysis can reveal previously undiagnosed mitochondrial diagnoses and modestly increase diagnostic yield in large rare-disease cohorts.

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2025-05-19.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 7
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- MToolBox/MITOMAP/MitoPhen-based reanalysis identified 136 mtDNA variants in 135 undiagnosed individuals and produced 37 confirmed or likely mtDNA diagnoses, yielding a 0.4% diagnos
- Phenotype similarity threshold of 0.3 provides high sensitivity; higher thresholds increase specificity; 92% of diagnosed/likely cases had a score > 0.3.
- All diagnostically relevant mtDNA variants were detectable in blood with heteroplasmy > 11%; lower blood heteroplasmy can hinder diagnosis.
- A homoplasmic MT-TL1 variant m.1555A>G confers risk for aminoglycoside-induced deafness; recognition enables avoidance of this drug.
- Incorporating focused mtDNA analysis and phenotype similarity scoring into routine exome/genome reanalysis can reveal actionable mitochondrial findings and modestly increase diagno
- Diversity of study populations is limited; European ancestry predominates (about 96%), underscoring the need for diverse cohorts to ensure generalizability.

QC result: Pass.