TERT and Intellectual disability: They also involve mutations in tumor-suppressive genes such as Neurofibromatosis type 1(NF1), Phosphatase and Tensin homolog (PTEN), tumor protein p53 (p53), and Retinoblastoma (RB) and in genes that are associated with metabolism and telomere length maintenance, like Isocitrate Dehydrogenase (IDH) isozyme genes and Telomerase Reverse Transcriptase (TERT), alpha-thalassemia/mental retardation, X-linked(ATRX), and Death domain Associated protein (DAXX), respectively.