Polymerase γ-related disorders (POLG-RDs)
General description
Polymerase γ-related disorders (POLG-RDs) represent a genetically heterogeneous group of mitochondrial diseases caused by mutations in the polymerase γ (POLG) gene, which encodes the sole DNA polymerase responsible for mitochondrial DNA (mtDNA) replication and repair. Several clinical phenotypes associated with POLG-RDs are known, including:
- Alpers-Huttenlocher syndrome
- Myocerebrohepatopathy spectrum
- Myoclonic epilepsy myopathy sensory ataxia (MENSA)
- Ataxia neuropathy spectrum (ANS)
- Spinocerebellar ataxia with epilepsy
- Progressive external ophthalmoplegia
POLG-RDs are the most common cause of mitochondrial epilepsy, with onset ranging from infancy to adulthood. Other manifestations include ophthalmoplegia, ataxia, regression of neurological symptoms, and hepatic damage.
References
- Gonçalves, F. G., et al. "The perirolandic sign: A unique imaging finding observed in association with polymerase γ-related disorders." American Journal of Neuroradiology 41.5 (2020): 917-922.
T2WI and FLAIR hyperintensity
Stroke-like DWI hyperintensity, along with T2WI and FLAIR hyperintensity, is most commonly observed in the occipital lobes. The bilateral thalamus, basal ganglia, and cerebellum may also show T2WI/FLAIR hyperintensity.
Perirolandic sign
A characteristic finding of this disease is unilateral or bilateral hyperintensity on T2WI, FLAIR, and DWI in the perirolandic cortex, involving either the precentral or postcentral gyri.