Fig. 4

Telomere alterations and contribution to NF1 tumorigenesis. In gliomagenesis, ATRX alterations and ALT are associated with high grade tumors, while longer telomeres (without ALT) are frequent in both high grade and low grade gliomas. In malignant nerve sheath tumors, there are two separate pathways, one that involves ALT (with or without ATRX alterations), and another that lacks ALT and ATRX alterations, but frequently has SUZ12 or EED alterations, loss of H3 K27 trimethylation and abnormally short telomeres. Some alterations are common to all malignant NF1-associated tumors, particularly CDKN2A deletions/mutations