POLG and Familial paroxysmal ataxia: CACNA1A variants have been reported in patients with episodic ataxia [24] and spinocerebellar ataxia [25]; however, in this patient, the initial targeted diagnostic screens prior to ES had focused on respiratory chain defects and common mitochondrial mutation analysis (including m.3243A>G, m.8993 T>C, POLG).