Keywords: AHS; Alpers-Huttenlocher Syndrome; EPC; epilepsia-partialis-continua; KSS; Kearns-Sayre Syndrome; MELAS; Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-like episodes; MIDD; Maternally Inherited Diabetes and Deafness; mtDNA; Mitochondrial DNA;