Identification of a novel likely pathogenic MT-TS2 variant in a patient with mitochondrial myopathy, retinitis pigmentosa and sensorineural hearing loss.
Madalena Couto, Mafalda Delgado Soares, Pedro Coelho et al.
✦ AI-curated · Sources linked
Case in brief
A 55-year-old male with Kallmann syndrome, retinitis pigmentosa, and congenital sensorineural hearing loss presented with generalized weakness and imbalance. Examination revealed muscle atrophy, hyporeflexia, and mild tetraparesis. Electromyography suggested proximal myopathy, and muscle biopsy confirmed mitochondrial myopathy. Mitochondrial DNA sequencing identified a likely pathogenic heteroplasmic MT-TS2 variant, with significant differences in heteroplasmy between blood and muscle tissue.
What made this case unusual
The identification of a novel MT-TS2 variant (m.12257G>A) with nearly 100% heteroplasmy in muscle tissue is noteworthy, highlighting the variant's potential pathogenicity.
Diagnostic / clinical pearl
Clinicians should consider comprehensive mitochondrial DNA analysis in patients with unexplained myopathy and associated systemic symptoms to identify potential pathogenic variants.
Why it matters
This case underscores the importance of recognizing the genetic complexity of mitochondrial diseases, which can significantly impact diagnosis and management.