TK2 and myelodysplastic syndrome: The mutations in many genes are associated with early onset hepatocerebral MDS, including POLG (Naviaux and Nguyen, 2004), TWNK (Sarzi et al., 2007), TK2 (Zhang et al., 2010), DGUOK (Mandel et al., 2001), and MPV17 (Wong et al., 2007).