Novel MTCYB mutation in a young patient with recurrent stroke-like episodes and status epilepticus

Area of Science:

• Genetics
• Mitochondrial Biology
• Neurology

Background:

• Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is a severe mitochondrial disorder.
• Common mutations in mitochondrial DNA (mtDNA) account for many MELAS cases.
• The mitochondrial cytochrome b gene (MTCYB) is crucial for respiratory chain complex III function.

Observation:

• A patient presented with recurrent stroke-like episodes and status epilepticus.
• Genetic analysis revealed a novel MTCYB mutation (m.15092G>A, predicting p.G116S).
• This mutation is distinct from common MELAS-associated mutations.

Findings:

• The novel MTCYB mutation was linked to MELAS diagnosis.
• In silico and Western blot analyses suggested impaired stability of respiratory chain complex III.
• Cytochrome b is the sole mtDNA-encoded subunit of complex III.

Implications:

• This study identifies a new genetic cause for MELAS and stroke-like episodes.
• It highlights the importance of sequencing MTCYB in patients with stroke-like episodes, especially when common MELAS mutations are absent.
• Understanding MTCYB mutations broadens diagnostic capabilities for mitochondrial disorders affecting the central nervous system.