Several follow-up studies encompassing thousands of central nervous system neoplasms have found similar frequencies of IDH1 and IDH2 mutations (Hartmann et al., 2009; Nobusawa et al., 2009; van den Bent et al., 2010; Jha et al., 2011; Thon et al., 2012). The gene discussed is IDH2; the disease is central nervous system neoplasm.