POLG and Epileptic encephalopathy: Notably, the Y831C mutation was observed in association with another pathogenic variant in the POLG gene (c.156_158dupGCA, p.Q52dup) in a patient with late-onset unclassified epileptic encephalopathy who presented with both electrical and neuroimaging posterior brain abnormalities; overall, this was compatible with those previously described in patients harboring variants in the POLG gene [38].