GPT and neuroblastoma: Of note, expression of the 5′−3′ exonuclease, EXO1, located on chromosome 1q43 and involved in DNA double strand break repair41,42, telomere replication, and t-loop formation43, was not only reduced in 1q42.2-deleted tumors but generally reduced in ALT-positive neuroblastomas (Supplementary Fig. 16c).