POLG and mitochondrial DNA depletion syndrome 4a: The common POLG p.A467T mutation has previously been reported as a homozygous mutation in ataxia, sensory neuropathy, dysphagia, epilepsy, Alpers disease, progressive external ophthalmoplegia (PEO), and sensory ataxic neuropathy, dysarthria, and opthalmoparesis (http://tools.niehs.nih.gov/polg) and in trans with p.L966R (Nguyen et al., 2006).