[MELAS syndrome masquerading as herpes encephalitis: genetic diagnosis]
Related Experiment Video
Updated: Oct 4, 2026
Modeling Mitochondrial Disease Using Brain Organoids: A Focus on Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes
Published on: October 10, 2025
M de Toledo1, J Díaz-Guzmán, D A Pérez-Martínez
1Servicio de Neurología; Hospital 12 de Octubre, Madrid, 28041, España. mdetoledo@yahoo.com
Introduction:
MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke like episodes) is a mitochondrial disease related to the mitochondrial DNA mutation. The tRNALeu(UUR) mutation at the base pair 3234 is associated to 80% of cases of MELAS syndrome. The onset with the stroke like episodes is often before the age 40. Herpes simplex encephalitis (HSE) presents as acute episodes of focal neurologic deficit that are often related to the temporal lobe. Occasionally MELAS syndrome and HSE may have a similar clinical presentation.
Clinical Case:
A 33-year-old woman presented with seizures and a right parietotemporal syndrome of acute onset. The differential diagnosis between HSE and MELAS syndrome was established. MELAS syndrome was suspected based on her phenotype. The diagnosis of MELAS syndrome was confirmed by the presence of the mitochondrial tRNALeu(UUR) mutation at the base pair 3243.
Conclusion:
The clinical presentation of the MELAS syndrome may mimic that of the HSE, and antiviral treatment should be given until the diagnosis of MELAS syndrome is definitive. The study of the mitochondrial DNA helps diagnosing in a non invasive way many patients with MELAS syndrome.
Insights
MELAS syndrome can mimic herpes simplex encephalitis, presenting similar neurological symptoms. Mitochondrial DNA testing confirms MELAS syndrome, aiding in accurate diagnosis and treatment.
Area of Science:
- Neurology
- Genetics
- Mitochondrial Diseases
Background:
- MELAS syndrome, a mitochondrial DNA disorder, often presents with stroke-like episodes before age 40.
- Herpes simplex encephalitis (HSE) causes acute focal neurological deficits, typically involving the temporal lobe.
- Both MELAS syndrome and HSE can exhibit similar clinical presentations, complicating diagnosis.
Observation:
- A 33-year-old woman experienced acute seizures and right parietotemporal neurological deficits.
- The clinical picture necessitated a differential diagnosis between HSE and MELAS syndrome.
- Her phenotype raised suspicion for MELAS syndrome.
Findings:
- The patient was diagnosed with MELAS syndrome.
- Confirmation was established through the detection of the mitochondrial tRNALeu(UUR) mutation at base pair 3243.
- This specific mutation accounts for 80% of MELAS syndrome cases.
Implications:
- Early recognition of overlapping symptoms is crucial for timely intervention.
- Antiviral treatment for HSE should be considered until MELAS syndrome is definitively diagnosed.
- Mitochondrial DNA analysis provides a non-invasive method for diagnosing MELAS syndrome.
Related Concept Videos
01:28Herpes
01:19Encephalitis l: Introduction
01:26Encephalitis ll: Pathophysiology
01:23Genital Herpes
01:25Arboviral Encephalitis