PHF6 and X-linked syndromic intellectual disability: Interestingly, germline mutations in two PHD family members, PHF8 and PHF6, have been identified as the cause of two X-linked mental retardation syndromes, namely Siderius X-linked mental retardation25 and Borjeson–Forssman–Lehmann syndrome26, and somatic PHF6 mutations have been found in T cell acute lymphoblastic27 and acute myeloid leukemias (AMLs)28.