The key diagnostic criteria for diffuse gliomas of adults are mutations in isocitrate dehydrogenase genes IDH1 and IDH2; other primary genetic markers include co-deletion 1p/19q, nuclear alpha-thalassemia/mental retardation X-linked syndrome (ATRX) gene mutations, loss of cyclin-dependent kinase inhibitor 2A (CDKN2A), EGFR amplification, combined gain of chromosome (chr) 7 and loss of chr 10 (7+/10−), and telomerase reverse transcriptase (TERT) promoter mutations [27]. This evidence concerns the gene CDKN2A and X-linked syndromic intellectual disability.