POLRMT mutations impair mitochondrial transcription causing neurological disease

Area of Science:

• Genetics
• Molecular Biology
• Neuroscience

Background:

• Over 300 variants in mitochondrial DNA polymerase gamma cause disease.
• No mitochondrial phenotypes were previously linked to POLRMT, the mitochondrial RNA polymerase.

Purpose of the Study:

• Characterize the clinical and molecular aspects of POLRMT variants.
• Establish defective mitochondrial transcription as a disease mechanism.

Main Methods:

• Massive parallel sequencing identified POLRMT variants in eight individuals.
• Analyzed patient fibroblasts for mitochondrial mRNA synthesis defects.
• Performed in vitro characterization of recombinant POLRMT mutants.

Main Results:

• Identified both recessive and dominant POLRMT variants.
• Patient fibroblasts showed impaired mitochondrial mRNA synthesis.
• Recombinant POLRMT mutants exhibited deleterious effects on mitochondrial transcription.

Conclusions:

• POLRMT variants cause disease through defective mitochondrial transcription.
• This study establishes POLRMT as a nuclear gene associated with mitochondrial disorders.
• Identified key clinical features including developmental delay and ophthalmoplegia.