Currently there is no cure available for MDS and to increase the understanding of the mechanisms behind the syndrome we previously generated and described a mouse strain deficient in TK2 (TK2−/−) that we use as a model for human TK2 deficiency, and human TK2 deficient infantile fatal encephalomyopathy in particular [15]. The gene discussed is TK2; the disease is mitochondrial DNA depletion syndrome, encephalomyopathic form with methylmalonic aciduria.