POLG is a gene encoding the catalytic subunit of mitochondrial DNA polymerase gamma and is susceptible in children with intractable epilepsy; it comprises three main domains: an N-terminal domain containing 3′ → 5′ exonuclease activity, a spacer domain and C-terminal domain, containing 5′ → 3′ DNA polymerase activity in three subdomains termed palm, fingers and thumb [53]. Here, POLG is linked to epilepsy.