These markers include mutations in phosphatase and tensin homolog (PTEN), alpha-thalassemia/mental retardation syndrome X-linked (ATRX), and telomerase reverse transcriptase (TERT), as well as CDKN2A/B homozygous deletions and epidermal growth factor receptor (EGFR) amplification. This evidence concerns the gene PTEN and X-linked syndromic intellectual disability.