Meningiomas have been found in more than 50% of patients with this common hereditary disorder and sporadic meningiomas show frequent mutations in the NF2 oncosupressor gene [ 3- 5].
It is well known that cancer tissues show frequent mutations even at SNP sites and the sequence variations in tumor tissues maybe be different from those of normal blood samples, which will almost certainly lead to questions of how to justify the tissue-with-blood comparisons.
Other tumours show frequent mutation in this gene, which often leads to resistance against chemotherapy.
Tumors from patients aged 5 16 years show frequent TP53 mutations, which are often germline, and amplifications of GLI2 and MYCN.
It is intriguing to note that several recent sequencing projects, including the The Cancer Genome Atlas (http://cancergenome.nih.gov/), have failed to show frequent inactivating mutations in the TRPM2 gene in PCa patients and in other tumor types (data not shown).
Cutaneous melanocytic nevi and melanomas show frequent oncogenic mutations in BRAF and NRAS, and consequent constitutive activation of the MAP-kinase pathway (Davies et al, 2002; Pollock et al, 2003).
In particular, primary glioblastomas show frequent EGFR amplification and PTEN mutation but lack IDH1 mutation, while secondary glioblastomas are characterized by frequent mutations in the TP53 and IDH1 genes, but lack EGFR amplification [ 73, 93] (Fig. 1).
The 3' end of the E2 gene (hypervariable region 1: HVR1) shows frequent mutations that have the nature of a quasispecies (QS), defined as a population of closely related but different viral genetic sequences co-existing in the host and evolving as a single unit [1].
Apart from showing distinct methylation patterns, the epitypes differed at the genomic level for alterations common in UC: Epitypes A and B showed frequent FGFR3 mutations and losses of 9q whereas Epitype C showed signs of genomic instability and frequent 6p amplifications.
As initial data have shown that a 5' poly(A) HT in inlA, which encodes the L. monocytogenes internalin A protein, shows frequent frameshift mutations that result in a truncated and inactive 8 aa peptide [ 7, 10], we used this gene as a model to further probe the contributions of HTs to phase-shifting and reversible gene inactivation in bacterial pathogens.
